diff --git a/example/.flutter-plugins-dependencies b/example/.flutter-plugins-dependencies
index ebd1aa0..59b6db4 100644
--- a/example/.flutter-plugins-dependencies
+++ b/example/.flutter-plugins-dependencies
@@ -1 +1 @@
-{"info":"This is a generated file; do not edit or check into version control.","plugins":{"ios":[{"name":"path_provider","path":"/Users/linyunhe/.pub-cache/hosted/pub.dartlang.org/path_provider-0.4.1/","dependencies":[]}],"android":[{"name":"path_provider","path":"/Users/linyunhe/.pub-cache/hosted/pub.dartlang.org/path_provider-0.4.1/","dependencies":[]}],"macos":[],"linux":[],"windows":[],"web":[]},"dependencyGraph":[{"name":"path_provider","dependencies":[]}],"date_created":"2021-06-08 17:37:57.339650","version":"1.22.6-xianyu"}
\ No newline at end of file
+{"info":"This is a generated file; do not edit or check into version control.","plugins":{"ios":[{"name":"path_provider","path":"/Users/lingyan/Downloads/flutter/.pub-cache/hosted/pub.flutter-io.cn/path_provider-0.4.1/","dependencies":[]}],"android":[{"name":"path_provider","path":"/Users/lingyan/Downloads/flutter/.pub-cache/hosted/pub.flutter-io.cn/path_provider-0.4.1/","dependencies":[]}],"macos":[],"linux":[],"windows":[],"web":[]},"dependencyGraph":[{"name":"path_provider","dependencies":[]}],"date_created":"2021-07-01 11:18:54.633183","version":"2.2.2"}
\ No newline at end of file
diff --git a/example/lib/app.dart b/example/lib/app.dart
index d6cbf4f..2f5d45a 100644
--- a/example/lib/app.dart
+++ b/example/lib/app.dart
@@ -28,10 +28,10 @@ Widget createApp() {
         /// 2. 参数2 当 AppStore.state 变化时, PageStore.state 该如何变化
         page.connectExtraStore<GlobalState>(GlobalStore.store,
             (Object pagestate, GlobalState appState) {
-          final GlobalBaseState p = pagestate;
+          final GlobalBaseState p = pagestate as dynamic;
           if (p.themeColor != appState.themeColor) {
             if (pagestate is Cloneable) {
-              final Object copy = pagestate.clone();
+              final dynamic copy = pagestate.clone();
               final GlobalBaseState newState = copy;
               newState.themeColor = appState.themeColor;
               return newState;
@@ -77,7 +77,7 @@ Widget createApp() {
     home: routes.buildPage('todo_list', null),
     onGenerateRoute: (RouteSettings settings) {
       return MaterialPageRoute<Object>(builder: (BuildContext context) {
-        return routes.buildPage(settings.name, settings.arguments);
+        return routes.buildPage(settings.name!, settings.arguments);
       });
     },
   );
@@ -87,7 +87,7 @@ Widget createApp() {
 /// 只针对页面的生命周期进行打印
 EffectMiddleware<T> _pageAnalyticsMiddleware<T>({String tag = 'redux'}) {
   return (AbstractLogic<dynamic> logic, Store<T> store) {
-    return (Effect<dynamic> effect) {
+    return (Effect<dynamic>? effect) {
       return (Action action, Context<dynamic> ctx) {
         if (logic is Page<dynamic, dynamic> && action.type is Lifecycle) {
           print('${logic.runtimeType} ${action.type.toString()} ');
diff --git a/example/lib/global_store/reducer.dart b/example/lib/global_store/reducer.dart
index 2596b0d..6a40766 100644
--- a/example/lib/global_store/reducer.dart
+++ b/example/lib/global_store/reducer.dart
@@ -11,18 +11,17 @@ Reducer<GlobalState> buildReducer() {
     <Object, Reducer<GlobalState>>{
       GlobalAction.changeThemeColor: _onchangeThemeColor,
     },
-  );
+  )!;
 }
 
-List<Color> _colors = <Color>[
-  Colors.green,
-  Colors.red,
-  Colors.black,
-  Colors.blue
-];
+List<Color> _colors = <Color>[Colors.green, Colors.red, Colors.black, Colors.blue];
 
 GlobalState _onchangeThemeColor(GlobalState state, Action action) {
-  final Color next =
-      _colors[((_colors.indexOf(state.themeColor) + 1) % _colors.length)];
-  return state.clone()..themeColor = next;
+  if (state.themeColor != null) {
+    final Color next =
+        /// todo(不确定)
+        _colors[((_colors.indexOf(state.themeColor!) + 1) % _colors.length)];
+    return state.clone()..themeColor = next;
+  }
+  return state.clone();
 }
diff --git a/example/lib/global_store/state.dart b/example/lib/global_store/state.dart
index ca8ef6a..c6931d0 100644
--- a/example/lib/global_store/state.dart
+++ b/example/lib/global_store/state.dart
@@ -3,13 +3,13 @@ import 'dart:ui';
 import 'package:fish_redux/fish_redux.dart';
 
 abstract class GlobalBaseState {
-  Color get themeColor;
-  set themeColor(Color color);
+  Color? get themeColor;
+  set themeColor(Color? color);
 }
 
 class GlobalState implements GlobalBaseState, Cloneable<GlobalState> {
   @override
-  Color themeColor;
+  Color? themeColor;
 
   @override
   GlobalState clone() {
diff --git a/example/lib/global_store/store.dart b/example/lib/global_store/store.dart
index 7d386c0..98e41e3 100644
--- a/example/lib/global_store/store.dart
+++ b/example/lib/global_store/store.dart
@@ -5,7 +5,7 @@ import 'state.dart';
 /// 建立一个AppStore
 /// 目前它的功能只有切换主题
 class GlobalStore {
-  static Store<GlobalState> _globalStore;
+   static  Store<GlobalState>? _globalStore;
 
   static Store<GlobalState> get store =>
       _globalStore ??= createStore<GlobalState>(GlobalState(), buildReducer());
diff --git a/example/lib/todo_edit_page/effect.dart b/example/lib/todo_edit_page/effect.dart
index 83f3e9f..0d4dd15 100644
--- a/example/lib/todo_edit_page/effect.dart
+++ b/example/lib/todo_edit_page/effect.dart
@@ -11,7 +11,7 @@ Effect<TodoEditState> buildEffect() {
   return combineEffects(<Object, Effect<TodoEditState>>{
     ToDoEditAction.onDone: _onDone,
     ToDoEditAction.onChangeTheme: _onChangeTheme,
-  });
+  })!;
 }
 
 void _onDone(Action action, Context<TodoEditState> ctx) {
diff --git a/example/lib/todo_edit_page/state.dart b/example/lib/todo_edit_page/state.dart
index 6523d4a..4881cf7 100644
--- a/example/lib/todo_edit_page/state.dart
+++ b/example/lib/todo_edit_page/state.dart
@@ -5,16 +5,16 @@ import '../global_store/state.dart';
 import '../todo_list_page/todo_component/component.dart';
 
 class TodoEditState implements GlobalBaseState, Cloneable<TodoEditState> {
-  ToDoState toDo;
+  late ToDoState toDo;
 
-  TextEditingController nameEditController;
-  TextEditingController descEditController;
+  late TextEditingController nameEditController;
+  late TextEditingController descEditController;
 
-  FocusNode focusNodeName;
-  FocusNode focusNodeDesc;
+  late FocusNode focusNodeName;
+  late FocusNode focusNodeDesc;
 
   @override
-  Color themeColor;
+   Color? themeColor;
 
   @override
   TodoEditState clone() {
@@ -28,7 +28,7 @@ class TodoEditState implements GlobalBaseState, Cloneable<TodoEditState> {
   }
 }
 
-TodoEditState initState(ToDoState arg) {
+TodoEditState initState(ToDoState? arg) {
   final TodoEditState state = TodoEditState();
   state.toDo = arg?.clone() ?? ToDoState();
   state.nameEditController = TextEditingController(text: arg?.title);
diff --git a/example/lib/todo_list_page/effect.dart b/example/lib/todo_list_page/effect.dart
index ce01fc3..eb35b3f 100644
--- a/example/lib/todo_list_page/effect.dart
+++ b/example/lib/todo_list_page/effect.dart
@@ -10,7 +10,7 @@ Effect<PageState> buildEffect() {
   return combineEffects(<Object, Effect<PageState>>{
     Lifecycle.initState: _init,
     PageAction.onAdd: _onAdd,
-  });
+  })!;
 }
 
 void _init(Action action, Context<PageState> ctx) {
diff --git a/example/lib/todo_list_page/flow_adapter/adapter.dart b/example/lib/todo_list_page/flow_adapter/adapter.dart
index 52209c4..ae1364c 100644
--- a/example/lib/todo_list_page/flow_adapter/adapter.dart
+++ b/example/lib/todo_list_page/flow_adapter/adapter.dart
@@ -5,13 +5,12 @@ import '../todo_component/component.dart';
 import 'reducer.dart';
 import 'connector.dart';
 
-FlowAdapter<PageState> get adapter =>
-    FlowAdapter<PageState>(
+FlowAdapter<PageState> get adapter => FlowAdapter<PageState>(
       reducer: buildReducer(),
-        view: (PageState state) =>
-            DependentArray<PageState>(
-              length: state.itemCount,
-              builder: (int index) {
-                return ToDoConnector(index: index) + ToDoComponent();
-              },
-            ));
+      view: (PageState state) => DependentArray<PageState>(
+        length: state.itemCount,
+        builder: (int index) {
+          return ToDoConnector(index: index) + ToDoComponent();
+        },
+      ),
+    );
diff --git a/example/lib/todo_list_page/flow_adapter/connector.dart b/example/lib/todo_list_page/flow_adapter/connector.dart
index 21c9415..5b0361f 100644
--- a/example/lib/todo_list_page/flow_adapter/connector.dart
+++ b/example/lib/todo_list_page/flow_adapter/connector.dart
@@ -6,20 +6,20 @@ import '../todo_component/component.dart';
 class ToDoConnector
     extends ConnOp<PageState, ToDoState> {
 
-      ToDoConnector({this.index});
+      ToDoConnector({required this.index});
 
       final int index;
 
   @override
-  ToDoState get(PageState state) {
-    if (index >= state.toDos.length) {
+  ToDoState? get(PageState? state) {
+    if (index >= state!.toDos!.length) {
       return null;
     }
-    return state.toDos[index];
+    return state.toDos?[index];
   }
 
   @override
   void set(PageState state, ToDoState subState) {
-    state.toDos[index] = subState;
+    state.toDos![index] = subState;
   }
 }
\ No newline at end of file
diff --git a/example/lib/todo_list_page/flow_adapter/reducer.dart b/example/lib/todo_list_page/flow_adapter/reducer.dart
index 5432d3c..fc5674e 100644
--- a/example/lib/todo_list_page/flow_adapter/reducer.dart
+++ b/example/lib/todo_list_page/flow_adapter/reducer.dart
@@ -6,20 +6,19 @@ import '../todo_component/action.dart' as todo_action;
 import '../todo_component/component.dart';
 
 Reducer<PageState> buildReducer() {
-  return asReducer(<Object, Reducer<PageState>>{
-    ToDoListAction.add: _add,
-    todo_action.ToDoAction.remove: _remove
-  });
+  return asReducer(<Object, Reducer<PageState>>{ToDoListAction.add: _add, todo_action.ToDoAction.remove: _remove})!;
 }
 
 PageState _add(PageState state, Action action) {
   final ToDoState toDo = action.payload;
-  return state.clone()..toDos = (state.toDos.toList()..add(toDo));
+  final List<ToDoState> list = state.toDos?.toList() ?? [];
+  list.add(toDo);
+  return state.clone()..toDos = list;
 }
 
 PageState _remove(PageState state, Action action) {
   final String unique = action.payload;
   return state.clone()
-    ..toDos = (state.toDos.toList()
+    ..toDos = (state.toDos?.toList() ?? []
       ..removeWhere((ToDoState state) => state.uniqueId == unique));
 }
diff --git a/example/lib/todo_list_page/list_adapter/reducer.dart b/example/lib/todo_list_page/list_adapter/reducer.dart
index bca34da..b13cff9 100644
--- a/example/lib/todo_list_page/list_adapter/reducer.dart
+++ b/example/lib/todo_list_page/list_adapter/reducer.dart
@@ -9,17 +9,19 @@ Reducer<PageState> buildReducer() {
   return asReducer(<Object, Reducer<PageState>>{
     ToDoListAction.add: _add,
     todo_action.ToDoAction.remove: _remove
-  });
+  })!;
 }
 
 PageState _add(PageState state, Action action) {
   final ToDoState toDo = action.payload;
-  return state.clone()..toDos = (state.toDos.toList()..add(toDo));
+  List<ToDoState> list = state.toDos?.toList() ?? [];
+  list.add(toDo);
+  return state.clone()..toDos = list;
 }
 
 PageState _remove(PageState state, Action action) {
   final String unique = action.payload;
   return state.clone()
-    ..toDos = (state.toDos.toList()
+    ..toDos = (state.toDos?.toList() ?? []
       ..removeWhere((ToDoState state) => state.uniqueId == unique));
 }
diff --git a/example/lib/todo_list_page/page.dart b/example/lib/todo_list_page/page.dart
index 19f433b..ab11ad3 100644
--- a/example/lib/todo_list_page/page.dart
+++ b/example/lib/todo_list_page/page.dart
@@ -1,7 +1,6 @@
 import 'package:fish_redux/fish_redux.dart';
 
 import 'effect.dart';
-import 'list_adapter/adapter.dart';
 import 'flow_adapter/adapter.dart';
 import 'reducer.dart';
 import 'report_component/component.dart';
diff --git a/example/lib/todo_list_page/reducer.dart b/example/lib/todo_list_page/reducer.dart
index da26848..64e67e9 100644
--- a/example/lib/todo_list_page/reducer.dart
+++ b/example/lib/todo_list_page/reducer.dart
@@ -7,7 +7,7 @@ import 'todo_component/component.dart';
 Reducer<PageState> buildReducer() {
   return asReducer(
     <Object, Reducer<PageState>>{PageAction.initToDos: _initToDosReducer},
-  );
+  )!;
 }
 
 PageState _initToDosReducer(PageState state, Action action) {
diff --git a/example/lib/todo_list_page/state.dart b/example/lib/todo_list_page/state.dart
index 4cf260a..8ffe030 100644
--- a/example/lib/todo_list_page/state.dart
+++ b/example/lib/todo_list_page/state.dart
@@ -7,10 +7,10 @@ import 'todo_component/component.dart';
 
 class PageState extends ItemListLike
     implements GlobalBaseState, Cloneable<PageState> {
-  List<ToDoState> toDos;
+   List<ToDoState>? toDos;
 
   @override
-  Color themeColor;
+  Color? themeColor;
 
   @override
   PageState clone() {
@@ -20,7 +20,7 @@ class PageState extends ItemListLike
   }
 
   @override
-  Object getItemData(int index) => toDos[index];
+  Object getItemData(int index) => toDos?.elementAt(index) as dynamic;
 
   @override
   String getItemType(int index) => 'toDo';
@@ -30,12 +30,12 @@ class PageState extends ItemListLike
 
   @override
   ItemListLike updateItemData(int index, Object data, bool isStateCopied) {
-    toDos[index] = data;
+    toDos?[index] = data as dynamic;
     return this;
   }
 }
 
-PageState initState(Map<String, dynamic> args) {
+PageState initState(Map<String, dynamic>? args) {
   //just demo, do nothing here...
   return PageState();
 }
@@ -45,15 +45,15 @@ class ReportConnector extends ConnOp<PageState, ReportState>
   @override
   ReportState computed(PageState state) {
     return ReportState()
-      ..done = state.toDos.where((ToDoState tds) => tds.isDone).length
-      ..total = state.toDos.length;
+      ..done = state.toDos?.where((ToDoState tds) => tds.isDone).length ?? 0
+      ..total = state.toDos?.length ?? 0;
   }
 
   @override
   List<dynamic> factors(PageState state) {
     return <int>[
-      state.toDos.where((ToDoState tds) => tds.isDone).length,
-      state.toDos.length
+      state.toDos?.where((ToDoState tds) => tds.isDone).length ?? 0,
+      state.toDos?.length ?? 0
     ];
   }
 
diff --git a/example/lib/todo_list_page/todo_component/effect.dart b/example/lib/todo_list_page/todo_component/effect.dart
index 9d003df..f004540 100644
--- a/example/lib/todo_list_page/todo_component/effect.dart
+++ b/example/lib/todo_list_page/todo_component/effect.dart
@@ -8,7 +8,7 @@ Effect<ToDoState> buildEffect() {
   return combineEffects(<Object, Effect<ToDoState>>{
     ToDoAction.onEdit: _onEdit,
     ToDoAction.onRemove: _onRemove,
-  });
+  })!;
 }
 
 void _onEdit(Action action, Context<ToDoState> ctx) {
@@ -27,7 +27,7 @@ void _onEdit(Action action, Context<ToDoState> ctx) {
 }
 
 void _onRemove(Action action, Context<ToDoState> ctx) async {
-  final String select = await showDialog<String>(
+  final String? select = await showDialog<String>(
       context: ctx.context,
       builder: (BuildContext buildContext) {
         return AlertDialog(
@@ -49,6 +49,6 @@ void _onRemove(Action action, Context<ToDoState> ctx) async {
       });
 
   if (select == 'Yes') {
-    ctx.dispatch(ToDoActionCreator.removeAction(ctx.state.uniqueId));
+    ctx.dispatch(ToDoActionCreator.removeAction(ctx.state.uniqueId!));
   }
 }
diff --git a/example/lib/todo_list_page/todo_component/reducer.dart b/example/lib/todo_list_page/todo_component/reducer.dart
index 2e28e8b..4c932bd 100644
--- a/example/lib/todo_list_page/todo_component/reducer.dart
+++ b/example/lib/todo_list_page/todo_component/reducer.dart
@@ -7,7 +7,7 @@ Reducer<ToDoState> buildReducer() {
   return asReducer(<Object, Reducer<ToDoState>>{
     ToDoAction.edit: _edit,
     ToDoAction.done: _markDone
-  });
+  })!;
 }
 
 ToDoState _edit(ToDoState state, Action action) {
diff --git a/example/lib/todo_list_page/todo_component/state.dart b/example/lib/todo_list_page/todo_component/state.dart
index d8e4d64..ca0c8d3 100644
--- a/example/lib/todo_list_page/todo_component/state.dart
+++ b/example/lib/todo_list_page/todo_component/state.dart
@@ -2,9 +2,9 @@ import 'package:fish_redux/fish_redux.dart';
 // import 'package:uuid/uuid.dart';
 
 class ToDoState implements Cloneable<ToDoState> {
-  String uniqueId;
-  String title;
-  String desc;
+  String? uniqueId;
+  String? title;
+  String? desc;
   bool isDone;
 
   static int _seed = 202103051044;
diff --git a/example/lib/todo_list_page/todo_component/view.dart b/example/lib/todo_list_page/todo_component/view.dart
index 32f9e4e..f9a964a 100644
--- a/example/lib/todo_list_page/todo_component/view.dart
+++ b/example/lib/todo_list_page/todo_component/view.dart
@@ -38,7 +38,7 @@ Widget buildView(
                           : const Icon(Icons.check_box_outline_blank))(),
                     ),
                     onTap: () {
-                      dispatch(ToDoActionCreator.doneAction(state.uniqueId));
+                      dispatch(ToDoActionCreator.doneAction(state.uniqueId!));
                     },
                   )
                 ],
@@ -63,7 +63,7 @@ Widget buildView(
                     child: const Icon(Icons.edit),
                   ),
                   onTap: () {
-                    dispatch(ToDoActionCreator.onEditAction(state.uniqueId));
+                    dispatch(ToDoActionCreator.onEditAction(state.uniqueId!));
                   },
                 )
               ],
@@ -72,7 +72,7 @@ Widget buildView(
         ],
       ),
       onLongPress: () {
-        dispatch(ToDoActionCreator.onRemoveAction(state.uniqueId));
+        dispatch(ToDoActionCreator.onRemoveAction(state.uniqueId!));
       },
     ),
   );
diff --git a/example/lib/todo_list_page/view.dart b/example/lib/todo_list_page/view.dart
index e4a7b69..13cbc1c 100644
--- a/example/lib/todo_list_page/view.dart
+++ b/example/lib/todo_list_page/view.dart
@@ -5,7 +5,7 @@ import 'action.dart';
 import 'state.dart';
 
 Widget buildView(PageState state, Dispatch dispatch, ViewService viewService) {
-  final ListAdapter adapter = viewService.buildAdapter();
+  final ListAdapter adapter = viewService.buildAdapter()!;
   return Scaffold(
     appBar: AppBar(
       backgroundColor: state.themeColor,
@@ -17,7 +17,7 @@ Widget buildView(PageState state, Dispatch dispatch, ViewService viewService) {
           viewService.buildComponent('report'),
           Expanded(
               child: ListView.builder(
-                  itemBuilder: adapter.itemBuilder,
+                  itemBuilder: adapter.itemBuilder!,
                   itemCount: adapter.itemCount))
         ],
       ),
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index c635dbc..ab189b4 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -10,7 +10,7 @@ description: Demonstrates how to use the fish_redux.
 version: 1.0.0+1
 
 environment:
-    sdk: '>=2.0.0-dev.68.0 <3.0.0'
+    sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
     fish_redux:
@@ -20,12 +20,9 @@ dependencies:
     path_provider: ^0.4.1 
 
 dev_dependencies:
-    test: ^1.3.0
     mockito: ^3.0.0
     flutter_driver:
         sdk: flutter
-    flutter_test:
-        sdk: flutter
 
 # For information on the generic Dart part of this file, see the
 # following page: https://www.dartlang.org/tools/pub/pubspec
diff --git a/lib/src/extensions/adapter_extensions.dart b/lib/src/extensions/adapter_extensions.dart
index 5b5f75d..7950086 100644
--- a/lib/src/extensions/adapter_extensions.dart
+++ b/lib/src/extensions/adapter_extensions.dart
@@ -9,11 +9,13 @@ import 'connector_extensions.dart';
 
 class SimpleFlowAdapter<T> extends FlowAdapter<T> {
   SimpleFlowAdapter({
-    @required FlowAdapterView<T> view,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    @deprecated Object Function(T state) key,
+    required FlowAdapterView<T> view,
+
+    /// 父类可空
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    @deprecated Object Function(T state)? key,
   }) : super(
           view: view,
           filter: filter,
@@ -23,11 +25,11 @@ class SimpleFlowAdapter<T> extends FlowAdapter<T> {
         );
 
   SimpleFlowAdapter.static({
-    @required List<Dependent<T>> children,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    @deprecated Object Function(T state) key,
+    required List<Dependent<T>> children,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    @deprecated Object Function(T state)? key,
   }) : this(
           view: _buildByStatic(children),
           filter: filter,
@@ -37,12 +39,12 @@ class SimpleFlowAdapter<T> extends FlowAdapter<T> {
         );
 
   SimpleFlowAdapter.dynamic({
-    @required Map<String, AbstractLogic<Object>> pool,
-    @required AbstractConnector<T, List<ItemBean>> connector,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    @deprecated Object Function(T state) key,
+    required Map<String, AbstractLogic<Object>> pool,
+    required AbstractConnector<T, List<ItemBean>> connector,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    @deprecated required Object Function(T state) key,
   }) : this(
           view: _buildByDynamic(pool: pool, connector: connector),
           filter: filter,
@@ -52,12 +54,12 @@ class SimpleFlowAdapter<T> extends FlowAdapter<T> {
         );
 
   SimpleFlowAdapter.listLike({
-    @required Map<String, AbstractLogic<Object>> pool,
-    @required AbstractConnector<T, MutableItemListLike> connector,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    @deprecated Object Function(T state) key,
+    required Map<String, AbstractLogic<Object>> pool,
+    required AbstractConnector<T, MutableItemListLike> connector,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    @deprecated required Object Function(T state) key,
   }) : this(
           view: _buildByListLike(pool: pool, connector: connector),
           filter: filter,
@@ -69,28 +71,28 @@ class SimpleFlowAdapter<T> extends FlowAdapter<T> {
 
 FlowAdapterView<T> _buildByStatic<T>(List<Dependent<T>> children) {
   return (T state) {
-    return DependentArray<T>.fromList(children
-        .where((Dependent<T> dep) => dep.subGetter(() => state).call() != null)
-        .toList());
+    return DependentArray<T>.fromList(
+        children.where((Dependent<T> dep) => dep.subGetter(() => state).call() != null).toList());
   };
 }
 
 FlowAdapterView<T> _buildByListLike<T>({
-  @required Map<String, AbstractLogic<Object>> pool,
-  @required AbstractConnector<T, MutableItemListLike> connector,
+  required Map<String, AbstractLogic<Object>> pool,
+  required AbstractConnector<T, MutableItemListLike> connector,
 }) {
   return (T state) {
-    final MutableItemListLike source = connector.get(state);
+    ///todo(不确定)
+    final MutableItemListLike source = connector.get(state)!;
     final DependentArray<T> depList = DependentArray<T>(
       length: source.itemCount,
       builder: (int index) {
         final String type = source.getItemType(index);
-        final Dependent<T> dep = ConnHelper.join(
+        final Dependent<T>? dep = ConnHelper.join(
           ConnHelper.to(
             connector,
             IndexedListLikeConn<MutableItemListLike>(index),
           ),
-          pool[type],
+          pool[type]!,
         );
         return dep;
       },
@@ -100,11 +102,12 @@ FlowAdapterView<T> _buildByListLike<T>({
 }
 
 FlowAdapterView<T> _buildByDynamic<T>({
-  @required Map<String, AbstractLogic<Object>> pool,
-  @required AbstractConnector<T, List<ItemBean>> connector,
+  required Map<String, AbstractLogic<Object>> pool,
+  required AbstractConnector<T, List<ItemBean>> connector,
 }) {
   return (T state) {
-    final List<ItemBean> list = connector.get(state);
+    ///todo(不确定)
+    final List<ItemBean> list = connector.get(state)!;
     final DependentArray<T> depList = DependentArray<T>(
       length: list.length,
       builder: (int index) {
@@ -117,7 +120,8 @@ FlowAdapterView<T> _buildByDynamic<T>({
               connector,
               IndexedListConn<ItemBean>(index),
             ),
-            pool[ib.type],
+            ///todo(不确定)
+            pool[ib.type]!,
           );
         }
         return null;
diff --git a/lib/src/extensions/component_extensions.dart b/lib/src/extensions/component_extensions.dart
index f09ea36..7edbd49 100644
--- a/lib/src/extensions/component_extensions.dart
+++ b/lib/src/extensions/component_extensions.dart
@@ -4,11 +4,11 @@ import 'package:flutter/widgets.dart' hide Action;
 
 abstract class SimpleComponent<T> extends Component<T> {
   SimpleComponent({
-    ReducerFilter<T> filter,
-    Dependencies<T> dependencies,
-    ShouldUpdate<T> shouldUpdate,
-    WidgetWrapper wrapper,
-    @deprecated Key Function(T) key,
+    ReducerFilter<T>? filter,
+    Dependencies<T>? dependencies,
+    ShouldUpdate<T>? shouldUpdate,
+    WidgetWrapper? wrapper,
+    @deprecated  Key Function(T)? key,
     bool clearOnDependenciesChanged = false,
   }) : super(
           view: null,
diff --git a/lib/src/extensions/connector_extensions.dart b/lib/src/extensions/connector_extensions.dart
index 5ca32de..7684d3c 100644
--- a/lib/src/extensions/connector_extensions.dart
+++ b/lib/src/extensions/connector_extensions.dart
@@ -5,21 +5,22 @@ import '../redux_component/basic.dart';
 import '../redux_connector/redux_connector.dart';
 
 mixin IndexedConnMixin<T, P> on AbstractConnector<T, P> {
-  P _cached;
+  late P _cached;
 
   int get index;
 
   P getByIndex(T state, int index);
 
   @override
-  P get(T state) {
-    final P newState = getByIndex(state, index);
-    return checkNextState(newState);
+  P? get(T? state) {
+    ///todo(不确定)
+    final P newState = getByIndex(state!, index);
+    return checkNextState(newState as dynamic);
   }
 
   /// fix get 存在状态不同步
   P checkNextState(Object newState) {
-    final Object lastState = _cached;
+    final Object lastState = _cached as Object;
     final Object nextState =
         ((newState is! P || newState.runtimeType != lastState.runtimeType)
                 ? false
@@ -27,7 +28,7 @@ mixin IndexedConnMixin<T, P> on AbstractConnector<T, P> {
                     (lastState is StateKey ? lastState.key() : null))
             ? newState
             : lastState;
-    return _cached = nextState;
+    return _cached = nextState as P;
   }
 }
 
@@ -63,11 +64,11 @@ class IndexedListConn<P> extends MutableIndexedConn<List<P>, P>
   @override
   P getByIndex(List<P> state, int index) {
     final P newState = state[index];
-    return checkNextState(newState);
+    return checkNextState(newState as Object);
   }
 
   @override
-  void setByIndex(List<P> state, Object subState, int index) {
+  void setByIndex(List<P> state, P subState, int index) {
     state[index] = subState;
   }
 }
diff --git a/lib/src/redux/apply_middleware.dart b/lib/src/redux/apply_middleware.dart
index c185d64..6efefa7 100644
--- a/lib/src/redux/apply_middleware.dart
+++ b/lib/src/redux/apply_middleware.dart
@@ -2,7 +2,8 @@ import 'basic.dart';
 
 /// Accumulate a list of Middleware that enhances Dispatch to the Store.
 /// The wrapped direction of the Store.dispatch is from inside to outside.
-StoreEnhancer<T> applyMiddleware<T>(List<Middleware<T>> middleware) {
+/// 可空 #7
+StoreEnhancer<T>? applyMiddleware<T>(List<Middleware<T>> middleware) {
   return middleware == null || middleware.isEmpty
       ? null
       : (StoreCreator<T> creator) => (T initState, Reducer<T> reducer) {
diff --git a/lib/src/redux/basic.dart b/lib/src/redux/basic.dart
index a372f3f..94fbe5a 100644
--- a/lib/src/redux/basic.dart
+++ b/lib/src/redux/basic.dart
@@ -28,7 +28,8 @@ class Action {
 
 /// Definition of the standard Reducer.
 /// If the Reducer needs to respond to the Action, it returns a new state, otherwise it returns the old state.
-typedef Reducer<T> = T Function(T state, Action action);
+/// 可空
+typedef Reducer<T> = T? Function(T state, Action action);
 
 /// Definition of the standard Dispatch.
 /// Send an "intention".
@@ -58,12 +59,12 @@ typedef Middleware<T> = Composable<Dispatch> Function({
 
 /// Definition of the standard Store.
 class Store<T> {
-  Get<T> getState;
-  Dispatch dispatch;
-  Subscribe subscribe;
-  Observable<T> observable;
-  ReplaceReducer<T> replaceReducer;
-  Future<dynamic> Function() teardown;
+  late Get<T> getState;
+  late Dispatch dispatch;
+  late Subscribe subscribe;
+  late Observable<T> observable;
+  late ReplaceReducer<T> replaceReducer;
+  late Future<dynamic> Function() teardown;
 }
 
 /// Create a store definition
@@ -85,7 +86,8 @@ typedef SubReducer<T> = T Function(T state, Action action, bool isStateCopied);
 /// 2. How to synchronize changes of an instance of type P to an instance of type S.
 /// 3. How to clone a new S.
 abstract class AbstractConnector<S, P> {
-  P get(S state);
+  /// 可空 【connector.dart#17】 [helper.dart#24] state?
+  P? get(S? state);
 
   /// For mutable state, there are three abilities needed to be met.
   ///     1. get: (S) => P
@@ -97,5 +99,6 @@ abstract class AbstractConnector<S, P> {
   ///     2. set: (S, P) => S
   ///
   /// See in [connector].
-  SubReducer<S> subReducer(Reducer<P> reducer);
+  /// 可空 【connector.dart#87】 [basic.dart#286] reducer?
+  SubReducer<S>? subReducer(Reducer<P>? reducer);
 }
diff --git a/lib/src/redux/combine_reducers.dart b/lib/src/redux/combine_reducers.dart
index d3d0e86..c15cb1f 100644
--- a/lib/src/redux/combine_reducers.dart
+++ b/lib/src/redux/combine_reducers.dart
@@ -1,36 +1,38 @@
 import 'basic.dart';
 
 /// Combine an iterable of SubReducer<T> into one Reducer<T>
-Reducer<T> combineSubReducers<T>(Iterable<SubReducer<T>> subReducers) {
-  final List<SubReducer<T>> notNullReducers = subReducers
-      ?.where((SubReducer<T> e) => e != null)
-      ?.toList(growable: false);
+/// 可空
+Reducer<T>? combineSubReducers<T>(Iterable<SubReducer<T>?> subReducers) {
+  final List<SubReducer<T>?>? notNullReducers = subReducers
+      .where((SubReducer<T>? e) => e != null)
+      .toList(growable: false);
 
   if (notNullReducers == null || notNullReducers.isEmpty) {
     return null;
   }
 
   if (notNullReducers.length == 1) {
-    final SubReducer<T> single = notNullReducers.single;
-    return (T state, Action action) => single(state, action, false);
+    final SubReducer<T>? single = notNullReducers.single;
+    return (T state, Action action) => single?.call(state, action, false);
   }
 
   return (T state, Action action) {
-    T copy = state;
+    T? _copy;
     bool hasChanged = false;
-    for (SubReducer<T> subReducer in notNullReducers) {
-      copy = subReducer(copy, action, hasChanged);
-      hasChanged = hasChanged || copy != state;
+    for (SubReducer<T>? subReducer in notNullReducers) {
+      _copy = subReducer?.call(state, action, hasChanged);
+      hasChanged = hasChanged || _copy != state;
     }
-    assert(copy != null);
-    return copy;
+    assert(_copy != null);
+    return _copy;
   };
 }
 
 /// Combine an iterable of Reducer<T> into one Reducer<T>
-Reducer<T> combineReducers<T>(Iterable<Reducer<T>> reducers) {
-  final List<Reducer<T>> notNullReducers =
-      reducers?.where((Reducer<T> r) => r != null)?.toList(growable: false);
+/// 可空
+Reducer<T>? combineReducers<T>(Iterable<Reducer<T>?>? reducers) {
+  final List<Reducer<T>?>? notNullReducers =
+      reducers?.where((Reducer<T>? r) => r != null).toList(growable: false);
   if (notNullReducers == null || notNullReducers.isEmpty) {
     return null;
   }
@@ -41,8 +43,10 @@ Reducer<T> combineReducers<T>(Iterable<Reducer<T>> reducers) {
 
   return (T state, Action action) {
     T nextState = state;
-    for (Reducer<T> reducer in notNullReducers) {
-      nextState = reducer(nextState, action);
+    for (Reducer<T>? reducer in notNullReducers) {
+      /// 这里有问题，必须要重新赋值对象
+      final T? _nextState = reducer?.call(nextState, action);
+      nextState = _nextState!;
     }
     assert(nextState != null);
     return nextState;
@@ -50,11 +54,12 @@ Reducer<T> combineReducers<T>(Iterable<Reducer<T>> reducers) {
 }
 
 /// Convert a super Reducer<Sup> to a sub Reducer<Sub>
-Reducer<Sub> castReducer<Sub extends Sup, Sup>(Reducer<Sup> sup) {
+/// 可空
+Reducer<Sub>? castReducer<Sub extends Sup, Sup>(Reducer<Sup>? sup) {
   return sup == null
       ? null
       : (Sub state, Action action) {
-          final Sub result = sup(state, action);
+          final Sub result = sup(state, action) as dynamic;
           return result;
         };
 }
diff --git a/lib/src/redux/connector.dart b/lib/src/redux/connector.dart
index 8e39009..cb23a16 100644
--- a/lib/src/redux/connector.dart
+++ b/lib/src/redux/connector.dart
@@ -19,16 +19,17 @@ abstract class ImmutableConn<T, P> implements AbstractConnector<T, P> {
 
   T set(T state, P subState);
 
+  /// 可空 reducer?
   @override
-  SubReducer<T> subReducer(Reducer<P> reducer) {
+  SubReducer<T>? subReducer(Reducer<P>? reducer) {
     return reducer == null
         ? null
         : (T state, Action action, bool isStateCopied) {
-            final P props = get(state);
+            final P? props = get(state);
             if (props == null) {
               return state;
             }
-            final P newProps = reducer(props, action);
+            final P newProps = reducer.call(props, action)!;
             final bool hasChanged = !identical(newProps, props);
             if (hasChanged) {
               final T result = set(state, newProps);
@@ -82,16 +83,17 @@ abstract class MutableConn<T, P> implements AbstractConnector<T, P> {
 
   void set(T state, P subState);
 
+  /// 可空
   @override
-  SubReducer<T> subReducer(Reducer<P> reducer) {
+  SubReducer<T>? subReducer(Reducer<P>? reducer) {
     return reducer == null
         ? null
         : (T state, Action action, bool isStateCopied) {
-            final P props = get(state);
+            final P? props = get(state);
             if (props == null) {
               return state;
             }
-            final P newProps = reducer(props, action);
+            final P newProps = reducer(props, action)!;
             final bool hasChanged = newProps != props;
             final T copy =
                 (hasChanged && !isStateCopied) ? _clone<T>(state) : state;
diff --git a/lib/src/redux/create_store.dart b/lib/src/redux/create_store.dart
index c2f1914..9301d91 100644
--- a/lib/src/redux/create_store.dart
+++ b/lib/src/redux/create_store.dart
@@ -6,13 +6,14 @@ Reducer<T> _noop<T>() => (T state, Action action) => state;
 
 typedef _VoidCallback = void Function();
 
-void _throwIfNot(bool condition, [String message]) {
+void _throwIfNot(bool condition, [dynamic message]) {
   if (!condition) {
     throw ArgumentError(message);
   }
 }
 
-Store<T> _createStore<T>(final T preloadedState, final Reducer<T> reducer) {
+/// 可空 reducer？
+Store<T> _createStore<T>(final T preloadedState, final Reducer<T>? reducer) {
   _throwIfNot(
     preloadedState != null,
     'Expected the preloadedState to be non-null value.',
@@ -41,7 +42,7 @@ Store<T> _createStore<T>(final T preloadedState, final Reducer<T> reducer) {
 
       try {
         _isDispatching = true;
-        _state = _reducer(_state, action);
+        _state = _reducer(_state, action)!;
       } finally {
         _isDispatching = false;
       }
@@ -55,8 +56,8 @@ Store<T> _createStore<T>(final T preloadedState, final Reducer<T> reducer) {
 
       _notifyController.add(_state);
     }
-    ..replaceReducer = (Reducer<T> replaceReducer) {
-      _reducer = replaceReducer ?? _noop;
+    ..replaceReducer = (Reducer<T>? replaceReducer) {
+      _reducer = replaceReducer ?? _noop as T Function(T, Action);
     }
     ..subscribe = (_VoidCallback listener) {
       _throwIfNot(
@@ -88,12 +89,14 @@ Store<T> _createStore<T>(final T preloadedState, final Reducer<T> reducer) {
 
 /// create a store with enhancer
 Store<T> createStore<T>(T preloadedState, Reducer<T> reducer,
-        [StoreEnhancer<T> enhancer]) =>
+        /// 可空
+        [StoreEnhancer<T>? enhancer]) =>
     enhancer != null
         ? enhancer(_createStore)(preloadedState, reducer)
         : _createStore(preloadedState, reducer);
 
-StoreEnhancer<T> composeStoreEnhancer<T>(List<StoreEnhancer<T>> enhancers) =>
+/// 可空 enhancers?
+StoreEnhancer<T>? composeStoreEnhancer<T>(List<StoreEnhancer<T>>? enhancers) =>
     enhancers == null || enhancers.isEmpty
         ? null
         : enhancers.reduce((StoreEnhancer<T> previous, StoreEnhancer<T> next) =>
diff --git a/lib/src/redux_adapter/adapter.dart b/lib/src/redux_adapter/adapter.dart
index 095ead5..fffc391 100644
--- a/lib/src/redux_adapter/adapter.dart
+++ b/lib/src/redux_adapter/adapter.dart
@@ -7,15 +7,17 @@ import '../redux_component/redux_component.dart';
 abstract class Adapter<T> extends Logic<T> implements AbstractAdapter<T> {
   final AdapterBuilder<T> _adapter;
 
-  AdapterBuilder<T> get protectedAdapter => _adapter;
+  AdapterBuilder<T>? get protectedAdapter => _adapter;
 
   Adapter({
-    @required AdapterBuilder<T> adapter,
-    Reducer<T> reducer,
-    ReducerFilter<T> filter,
-    Effect<T> effect,
-    Dependencies<T> dependencies,
-    @deprecated Object Function(T) key,
+    required AdapterBuilder<T> adapter,
+    /// 可空
+    Reducer<T>? reducer,
+    /// 可空
+    ReducerFilter<T>? filter,
+    Effect<T>? effect,
+    Dependencies<T>? dependencies,
+    @deprecated Object Function(T)? key,
   })  : assert(adapter != null),
         assert(dependencies?.adapter == null,
             'Unexpected dependencies.list for Adapter.'),
@@ -30,7 +32,7 @@ abstract class Adapter<T> extends Logic<T> implements AbstractAdapter<T> {
         );
 
   @override
-  ListAdapter buildAdapter(ContextSys<T> ctx) =>
+  ListAdapter? buildAdapter(ContextSys<T> ctx) =>
       ctx.enhancer
           ?.adapterEnhance(protectedAdapter, this, ctx.store)
           ?.call(ctx.state, ctx.dispatch, ctx) ??
@@ -41,8 +43,8 @@ abstract class Adapter<T> extends Logic<T> implements AbstractAdapter<T> {
     Store<Object> store,
     BuildContext buildContext,
     Get<T> getState, {
-    @required Enhancer<Object> enhancer,
-    @required DispatchBus bus,
+    required Enhancer<Object> enhancer,
+    required DispatchBus bus,
   }) {
     assert(bus != null && enhancer != null);
     return AdapterContext<T>(
@@ -58,12 +60,12 @@ abstract class Adapter<T> extends Logic<T> implements AbstractAdapter<T> {
 
 class AdapterContext<T> extends LogicContext<T> {
   AdapterContext({
-    @required AbstractAdapter<T> logic,
-    @required Store<Object> store,
-    @required BuildContext buildContext,
-    @required Get<T> getState,
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required AbstractAdapter<T> logic,
+    required Store<Object> store,
+    required BuildContext buildContext,
+    required Get<T> getState,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   })  : assert(bus != null && enhancer != null),
         super(
           logic: logic,
@@ -75,8 +77,8 @@ class AdapterContext<T> extends LogicContext<T> {
         );
 
   @override
-  ListAdapter buildAdapter() {
-    final AbstractAdapter<T> curLogic = logic;
+  ListAdapter? buildAdapter() {
+    final AbstractAdapter<T?> curLogic = logic as dynamic;
     return curLogic.buildAdapter(this);
   }
 }
diff --git a/lib/src/redux_adapter/dynamic_flow_adapter.dart b/lib/src/redux_adapter/dynamic_flow_adapter.dart
index 8bc9fd6..638540c 100644
--- a/lib/src/redux_adapter/dynamic_flow_adapter.dart
+++ b/lib/src/redux_adapter/dynamic_flow_adapter.dart
@@ -15,18 +15,18 @@ class DynamicFlowAdapter<T> extends Logic<T> with RecycleContextMixin<T> {
   final AbstractConnector<T, List<ItemBean>> connector;
 
   DynamicFlowAdapter({
-    @required this.pool,
-    @required this.connector,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
+    required this.pool,
+    required this.connector,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
 
     /// implement [StateKey] in T instead of using key in Logic.
     /// class T implements StateKey {
     ///   Object _key = UniqueKey();
     ///   Object key() => _key;
     /// }
-    @deprecated Object Function(T) key,
+    @deprecated Object Function(T)? key,
   }) : super(
           reducer: _dynamicReducer(reducer, pool, connector),
           effect: effect,
@@ -36,12 +36,14 @@ class DynamicFlowAdapter<T> extends Logic<T> with RecycleContextMixin<T> {
           key: key,
         );
 
+  /// 可空
   @override
-  ListAdapter buildAdapter(ContextSys<T> ctx) {
-    final List<ItemBean> list = connector.get(ctx.state);
+  ListAdapter? buildAdapter(ContextSys<T> ctx) {
+    ///todo(不确定)
+    final List<ItemBean> list = connector.get(ctx.state)!;
     assert(list != null);
 
-    final RecycleContext<T> recycleCtx = ctx;
+    final RecycleContext<T> recycleCtx = ctx as dynamic;
     final List<ListAdapter> adapters = <ListAdapter>[];
 
     recycleCtx.markAllUnused();
@@ -49,9 +51,8 @@ class DynamicFlowAdapter<T> extends Logic<T> with RecycleContextMixin<T> {
     for (int index = 0; index < list.length; index++) {
       final ItemBean itemBean = list[index];
       final String type = itemBean.type;
-      final AbstractLogic<Object> result = pool[type];
-      assert(
-          result != null, 'Type of $type has not benn registered in the pool.');
+      final AbstractLogic<Object> result = pool[type]!;
+      assert(result != null, 'Type of $type has not benn registered in the pool.');
       if (result != null) {
         if (result is AbstractAdapter<Object>) {
           final ContextSys<Object> subCtx = recycleCtx.reuseOrCreate(
@@ -62,19 +63,23 @@ class DynamicFlowAdapter<T> extends Logic<T> with RecycleContextMixin<T> {
             () => result.createContext(
               recycleCtx.store,
               recycleCtx.context,
-              _subGetter(() => connector.get(recycleCtx.state), index),
+
+              /// todo(不确定)
+              _subGetter(() => connector.get(recycleCtx.state)!, index),
               bus: recycleCtx.bus,
               enhancer: recycleCtx.enhancer,
             ),
           );
 
           /// hack to reduce adapter's rebuilding
-          adapters.add(memoizeListAdapter(result, subCtx));
+          adapters.add(memoizeListAdapter(result as AbstractAdapterBuilder<Object>, subCtx));
         } else if (result is AbstractComponent<Object>) {
           adapters.add(ListAdapter((BuildContext buildContext, int _) {
             return result.buildComponent(
               recycleCtx.store,
-              _subGetter(() => connector.get(recycleCtx.state), index),
+
+              /// todo(不确定)
+              _subGetter(() => connector.get(recycleCtx.state)!, index),
               bus: recycleCtx.bus,
               enhancer: recycleCtx.enhancer,
             );
@@ -89,17 +94,17 @@ class DynamicFlowAdapter<T> extends Logic<T> with RecycleContextMixin<T> {
 }
 
 /// Generate reducer for List<ItemBean> and combine them into one
-Reducer<T> _dynamicReducer<T>(
-  Reducer<T> reducer,
+/// 可空
+Reducer<T>? _dynamicReducer<T>(
+  Reducer<T>? reducer,
   Map<String, AbstractLogic<Object>> pool,
   AbstractConnector<T, List<ItemBean>> connector,
 ) {
-  final Reducer<List<ItemBean>> dyReducer =
-      (List<ItemBean> state, Action action) {
-    List<ItemBean> copy;
+  final Reducer<List<ItemBean>> dyReducer = (List<ItemBean> state, Action action) {
+    List<ItemBean>? copy;
     for (int i = 0; i < state.length; i++) {
       final ItemBean itemBean = state[i];
-      final AbstractLogic<Object> result = pool[itemBean.type];
+      final AbstractLogic<Object>? result = pool[itemBean.type];
       if (result != null) {
         final Object newData = result.onReducer(itemBean.data, action);
         if (newData != itemBean.data) {
@@ -111,9 +116,9 @@ Reducer<T> _dynamicReducer<T>(
     return copy ?? state;
   };
 
-  return combineReducers(<Reducer<T>>[
+  return combineReducers(<Reducer<T>?>[
     reducer,
-    combineSubReducers(<SubReducer<T>>[connector.subReducer(dyReducer)]),
+    combineSubReducers(<SubReducer<T>?>[connector.subReducer(dyReducer)]),
   ]);
 }
 
@@ -128,7 +133,7 @@ Get<Object> _subGetter(Get<List<ItemBean>> getter, int index) {
   ItemBean cacheItem = curState[index];
 
   return () {
-    final List<ItemBean> newState = getter();
+    final List<ItemBean>? newState = getter();
 
     /// Either all sub-components use cache or not.
     if (newState != null && newState.length > index) {
@@ -142,18 +147,18 @@ Get<Object> _subGetter(Get<List<ItemBean>> getter, int index) {
   };
 }
 
-bool _couldReuse(ItemBean beanA, ItemBean beanB) {
-  if (beanA.type != beanB.type) {
+bool _couldReuse(ItemBean? beanA, ItemBean? beanB) {
+  if (beanA?.type != beanB?.type) {
     return false;
   }
 
-  final Object dataA = beanA.data;
-  final Object dataB = beanB.data;
+  final Object? dataA = beanA?.data;
+  final Object? dataB = beanB?.data;
   if (dataA.runtimeType != dataB.runtimeType) {
     return false;
   }
 
-  final Object keyA = dataA is StateKey ? dataA.key() : null;
-  final Object keyB = dataB is StateKey ? dataB.key() : null;
+  final Object? keyA = dataA is StateKey ? dataA.key() : null;
+  final Object? keyB = dataB is StateKey ? dataB.key() : null;
   return keyA == keyB;
 }
diff --git a/lib/src/redux_adapter/flow_adapter.dart b/lib/src/redux_adapter/flow_adapter.dart
index 43df0f9..b11fcfc 100644
--- a/lib/src/redux_adapter/flow_adapter.dart
+++ b/lib/src/redux_adapter/flow_adapter.dart
@@ -9,11 +9,11 @@ class FlowAdapter<T> extends Logic<T>
     implements AbstractAdapter<T> {
   final FlowDependencies<T> _flowDependencies;
   FlowAdapter({
-    @required FlowAdapterView<T> view,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    @deprecated Object Function(T state) key,
+    required FlowAdapterView<T> view,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    @deprecated Object Function(T state)? key,
   })  : assert(view != null),
         _flowDependencies =
             FlowDependencies<T>(_memoize<T, DependentArray<T>>(view)),
@@ -34,14 +34,14 @@ class FlowAdapter<T> extends Logic<T>
     final T state = ctx.state;
     final DependentArray<T> depArray = _flowDependencies.build(state);
 
-    final RecycleContext<T> recycleCtx = ctx;
+    final RecycleContext<T> recycleCtx = ctx as dynamic;
     final List<ListAdapter> adapters = <ListAdapter>[];
 
     recycleCtx.markAllUnused();
 
     final int count = depArray.length;
     for (int index = 0; index < count; index++) {
-      final Dependent<T> dependent = depArray[index];
+      final Dependent<T>? dependent = depArray[index];
 
       if (dependent == null) {
         continue;
@@ -62,7 +62,7 @@ class FlowAdapter<T> extends Logic<T>
           },
         );
 
-        adapters.add(dependent.buildAdapter(subCtx));
+        adapters.add(dependent.buildAdapter(subCtx)!);
       } else if (dependent.isComponent()) {
         adapters.add(ListAdapter((BuildContext buildContext, int index) {
           return dependent.buildComponent(
@@ -81,19 +81,19 @@ class FlowAdapter<T> extends Logic<T>
 }
 
 //////////////////////////////////////////
-typedef IndexedDependentBuilder<T> = Dependent<T> Function(int);
+typedef IndexedDependentBuilder<T> = Dependent<T>? Function(int);
 
 class DependentArray<T> {
   final IndexedDependentBuilder<T> builder;
   final int length;
 
-  DependentArray({@required this.builder, @required this.length})
+  DependentArray({required this.builder, required this.length})
       : assert(builder != null && length >= 0);
 
   DependentArray.fromList(List<Dependent<T>> list)
       : this(builder: (int index) => list[index], length: list.length);
 
-  Dependent<T> operator [](int index) => builder(index);
+  Dependent<T>? operator [](int index) => builder(index);
 }
 
 typedef FlowAdapterView<T> = DependentArray<T> Function(T);
@@ -106,11 +106,11 @@ class FlowDependencies<T> {
   Reducer<T> createReducer() => (T state, Action action) {
         T copy = state;
         bool hasChanged = false;
-        final DependentArray<T> list = build(state);
+        final DependentArray<T>? list = build(state);
         if (list != null) {
           for (int i = 0; i < list.length; i++) {
-            final Dependent<T> dep = list[i];
-            final SubReducer<T> subReducer = dep?.createSubReducer();
+            final Dependent<T>? dep = list[i];
+            final SubReducer<T>? subReducer = dep?.createSubReducer();
             if (subReducer != null) {
               copy = subReducer(copy, action, hasChanged);
               hasChanged = hasChanged || copy != state;
@@ -166,15 +166,16 @@ class ItemBean {
 
   const ItemBean(this.type, this.data);
 
-  ItemBean clone({String type, Object data}) =>
+  /// 可空
+  ItemBean clone({String? type, Object? data}) =>
       ItemBean(type ?? this.type, data ?? this.data);
 }
 
 /// Optimize flow-adapter-view performance
 R Function(P) _memoize<P, R>(R Function(P) functor) {
   bool hasInvoked = false;
-  P cahcedKey;
-  R cachedValue;
+  late P cahcedKey;
+  late R cachedValue;
   return (P param) {
     if (!hasInvoked) {
       hasInvoked = true;
diff --git a/lib/src/redux_adapter/recycle_context.dart b/lib/src/redux_adapter/recycle_context.dart
index 7421590..47aa11e 100644
--- a/lib/src/redux_adapter/recycle_context.dart
+++ b/lib/src/redux_adapter/recycle_context.dart
@@ -10,12 +10,12 @@ class RecycleContext<T> extends AdapterContext<T> {
   final Map<Object, int> _usedIndexMap = <Object, int>{};
 
   RecycleContext({
-    @required AbstractAdapter<T> logic,
-    @required @required Store<Object> store,
-    @required BuildContext buildContext,
-    @required Get<T> getState,
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required AbstractAdapter<T> logic,
+    @required required Store<Object> store,
+    required BuildContext buildContext,
+    required Get<T> getState,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   }) : super(
           logic: logic,
           store: store,
@@ -27,8 +27,8 @@ class RecycleContext<T> extends AdapterContext<T> {
 
   @override
   void onLifecycle(Action action) {
-    _cachedMap.forEach((Object key, List<ContextSys<Object>> list) {
-      for (ContextSys<Object> sub in list) {
+    _cachedMap.forEach((Object key, List<ContextSys<Object?>> list) {
+      for (ContextSys<Object?> sub in list) {
         sub.onLifecycle(action);
       }
     });
@@ -46,7 +46,7 @@ class RecycleContext<T> extends AdapterContext<T> {
         _cachedMap[key] ??= <ContextSys<Object>>[];
 
     if (length > list.length) {
-      _cachedMap[key].add(
+      _cachedMap[key]?.add(
         create()
           ..setParent(this)
           ..onLifecycle(LifecycleCreator.initState()),
@@ -76,9 +76,9 @@ mixin RecycleContextMixin<T> implements AbstractAdapter<T> {
   RecycleContext<T> createContext(
     Store<Object> store,
     BuildContext buildContext,
-    Get<Object> getState, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    Get<T> getState, {
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   }) {
     assert(bus != null && enhancer != null);
 
@@ -102,7 +102,8 @@ ListAdapter combineListAdapters(Iterable<ListAdapter> adapters) {
     /// The result is AbstractComponent
     return ListAdapter(
       (BuildContext buildContext, final int index) =>
-          list[index].itemBuilder(buildContext, 0),
+      ///todo(不确定)
+          list[index].itemBuilder!(buildContext, 0),
       list.length,
     );
   } else if (list.length == 1) {
@@ -124,7 +125,8 @@ ListAdapter combineListAdapters(Iterable<ListAdapter> adapters) {
         xIndex++;
       }
       assert(xIndex < list.length);
-      return list[xIndex].itemBuilder(buildContext, yIndex);
+      ///todo(不确定)
+      return list[xIndex].itemBuilder!(buildContext, yIndex);
     },
     maxItemCount,
   );
@@ -138,18 +140,20 @@ ListAdapter memoizeListAdapter(
   if (subCtx.extra['@last-state'] != newState) {
     subCtx.extra['@last-state'] = newState;
     subCtx.extra['@last-adapter'] =
-        _memoizeListAdapter(result.buildAdapter(subCtx));
+       ///todo(不确定)
+        _memoizeListAdapter(result.buildAdapter(subCtx)!);
   }
 
-  return subCtx.extra['@last-adapter'];
+  return subCtx.extra['@last-adapter'] as ListAdapter;
 }
 
 ListAdapter _memoizeListAdapter(ListAdapter adapter) {
   if (adapter.itemCount > 0) {
-    final List<Widget> memoized =
-        List<Widget>.filled(adapter.itemCount, null, growable: false);
+    final List<Widget?> memoized =
+        List<Widget?>.filled(adapter.itemCount, null, growable: false);
     return ListAdapter((BuildContext context, int index) {
-      return (memoized[index] ??= adapter.itemBuilder(context, index));
+      ///todo(不确定)
+      return (memoized[index] ??= adapter.itemBuilder!(context, index));
     }, adapter.itemCount);
   } else {
     return adapter;
diff --git a/lib/src/redux_adapter/source_flow_adapter.dart b/lib/src/redux_adapter/source_flow_adapter.dart
index 0f2aeba..926b950 100644
--- a/lib/src/redux_adapter/source_flow_adapter.dart
+++ b/lib/src/redux_adapter/source_flow_adapter.dart
@@ -11,22 +11,21 @@ import 'recycle_context.dart';
 /// see in example
 /// template is a map, driven by source
 @deprecated
-class SourceFlowAdapter<T extends ItemListLike> extends Logic<T>
-    with RecycleContextMixin<T> {
+class SourceFlowAdapter<T extends ItemListLike> extends Logic<T> with RecycleContextMixin<T> {
   final Map<String, AbstractLogic<Object>> pool;
 
   SourceFlowAdapter({
-    @required this.pool,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
+    required this.pool,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
 
     /// implement [StateKey] in T instead of using key in Logic.
     /// class T implements StateKey {
     ///   Object _key = UniqueKey();
     ///   Object key() => _key;
     /// }
-    @deprecated Object Function(T) key,
+    @deprecated  Object Function(T)? key,
   }) : super(
           reducer: _dynamicReducer(reducer, pool),
           effect: effect,
@@ -41,14 +40,14 @@ class SourceFlowAdapter<T extends ItemListLike> extends Logic<T>
     final ItemListLike adapterSource = ctx.state;
     assert(adapterSource != null);
 
-    final RecycleContext<T> recycleCtx = ctx;
+    final RecycleContext<T> recycleCtx = ctx as RecycleContext<T>;
     final List<ListAdapter> adapters = <ListAdapter>[];
 
     recycleCtx.markAllUnused();
 
     for (int index = 0; index < adapterSource.itemCount; index++) {
       final String type = adapterSource.getItemType(index);
-      final AbstractLogic<Object> result = pool[type];
+      final AbstractLogic<Object>? result = pool[type];
 
       assert(
           result != null, 'Type of $type has not benn registered in the pool.');
@@ -89,14 +88,15 @@ class SourceFlowAdapter<T extends ItemListLike> extends Logic<T>
 }
 
 /// Generate reducer for List<ItemBean> and combine them into one
-Reducer<T> _dynamicReducer<T extends ItemListLike>(
-  Reducer<T> reducer,
+/// 可空
+Reducer<T>? _dynamicReducer<T extends ItemListLike>(
+  Reducer<T>? reducer,
   Map<String, AbstractLogic<Object>> pool,
 ) {
   final Reducer<T> dyReducer = (ItemListLike state, Action action) {
-    ItemListLike copy;
+    ItemListLike? copy;
     for (int i = 0; i < state.itemCount; i++) {
-      final AbstractLogic<Object> result = pool[state.getItemType(i)];
+      final AbstractLogic<Object>? result = pool[state.getItemType(i)];
       if (result != null) {
         final Object oldData = state.getItemData(i);
         final Object newData = result.onReducer(oldData, action);
@@ -105,10 +105,13 @@ Reducer<T> _dynamicReducer<T extends ItemListLike>(
         }
       }
     }
-    return copy ?? state;
+    if (copy == null) {
+      return state is T ? state : null;
+    }
+    return copy is T ? copy : null;
   };
 
-  return combineReducers(<Reducer<T>>[reducer, dyReducer]);
+  return combineReducers(<Reducer<T>?>[reducer, dyReducer]);
 }
 
 /// Define itemBean how to get state with connector
@@ -145,11 +148,10 @@ Get<Object> _subGetter(Get<ItemListLike> getter, int index) {
   };
 }
 
-bool _couldReuse({String typeA, String typeB, Object dataA, Object dataB}) {
+bool _couldReuse({String? typeA, String? typeB, Object? dataA, Object? dataB}) {
   return typeA != typeB
       ? false
       : dataA.runtimeType != dataB.runtimeType
           ? false
-          : (dataA is StateKey ? dataA.key() : null) ==
-              (dataB is StateKey ? dataB.key() : null);
+          : (dataA is StateKey ? dataA.key() : null) == (dataB is StateKey ? dataB.key() : null);
 }
diff --git a/lib/src/redux_adapter/static_flow_adapter.dart b/lib/src/redux_adapter/static_flow_adapter.dart
index 9517993..93eada5 100644
--- a/lib/src/redux_adapter/static_flow_adapter.dart
+++ b/lib/src/redux_adapter/static_flow_adapter.dart
@@ -16,25 +16,25 @@ class StaticFlowAdapter<T> extends Logic<T>
   final List<Dependent<T>> _slots;
 
   StaticFlowAdapter({
-    @required List<Dependent<T>> slots,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    ReducerFilter<T> filter,
+    required List<Dependent<T>> slots,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    ReducerFilter<T>? filter,
 
     /// implement [StateKey] in T instead of using key in Logic.
     /// class T implements StateKey {
     ///   Object _key = UniqueKey();
     ///   Object key() => _key;
     /// }
-    @deprecated Object Function(T) key,
+    @deprecated  Object Function(T)? key,
   })  : assert(slots != null),
-        _slots = Collections.compact(slots),
+        _slots = Collections.compact(slots)!,
         super(
-          reducer: combineReducers(<Reducer<T>>[
+          reducer: combineReducers(<Reducer<T>?>[
             reducer,
             combineSubReducers(
               slots.map(
-                (Dependent<T> dependent) => dependent?.createSubReducer(),
+                (Dependent<T>? dependent) => dependent?.createSubReducer(),
               ),
             )
           ]),
@@ -47,7 +47,7 @@ class StaticFlowAdapter<T> extends Logic<T>
 
   @override
   ListAdapter buildAdapter(ContextSys<T> ctx) {
-    final RecycleContext<T> recycleCtx = ctx;
+    final RecycleContext<T> recycleCtx = ctx as RecycleContext<T>;
     final List<ListAdapter> adapters = <ListAdapter>[];
 
     recycleCtx.markAllUnused();
diff --git a/lib/src/redux_aop/aop.dart b/lib/src/redux_aop/aop.dart
index 27af42e..92c8618 100644
--- a/lib/src/redux_aop/aop.dart
+++ b/lib/src/redux_aop/aop.dart
@@ -8,7 +8,7 @@ typedef ApplyLikeEnhancer = ApplyLike Function(ApplyLike functor);
 
 ApplyLike _identity(ApplyLike f) => f;
 
-ApplyLikeEnhancer _combine(ApplyLikeEnhancer e0, ApplyLikeEnhancer e1) =>
+ApplyLikeEnhancer _combine(ApplyLikeEnhancer? e0, ApplyLikeEnhancer? e1) =>
     (ApplyLike f) => (e1 ?? _identity)((e0 ?? _identity)(f));
 
 const ApplyLikeEnhancer ApplyLikeEnhancerIdentity = _identity;
@@ -26,15 +26,15 @@ const ApplyLikeEnhancer ApplyLikeEnhancerIdentity = _identity;
 class AOP {
   final ApplyLikeEnhancer _enhancer;
 
-  AOP(List<ApplyLikeEnhancer> enhances)
+  AOP(List<ApplyLikeEnhancer>? enhances)
       : _enhancer = enhances?.isNotEmpty == true
-            ? enhances.reduce(_combine)
+            ? enhances!.reduce(_combine)
             : ApplyLikeEnhancerIdentity;
 
-  TypedApplyLike<R> enhance<R>(Function functor) {
+  TypedApplyLike<R>? enhance<R>(Function functor) {
     /// cast functor to ApplyLike
     final ApplyLike init = (List<dynamic> positionalArguments,
-            [Map<Symbol, dynamic> namedArguments]) =>
+            [Map<Symbol, dynamic>? namedArguments]) =>
         Function.apply(functor, positionalArguments, namedArguments);
 
     /// enhance ApplyLike
@@ -47,54 +47,54 @@ class AOP {
 
     /// cast ApplyLike to TypedApplyLike<R>
     return (List<dynamic> positionalArguments,
-        [Map<Symbol, dynamic> namedArguments]) {
+        [Map<Symbol, dynamic>? namedArguments]) {
       final R result = enhanced(positionalArguments);
       return result;
     };
   }
 
-  R Function() withZero<R>(R Function() f) {
-    final TypedApplyLike<R> enhanced = enhance<R>(f);
+  R? Function() withZero<R>(R Function() f) {
+    final TypedApplyLike<R?>? enhanced = enhance<R>(f);
     return enhanced != null ? () => enhanced(<dynamic>[]) : f;
   }
 
-  R Function(P) withOne<R, P>(R Function(P) f) {
-    final TypedApplyLike<R> enhanced = enhance<R>(f);
+  R? Function(P) withOne<R, P>(R Function(P) f) {
+    final TypedApplyLike<R?>? enhanced = enhance<R>(f);
     return enhanced != null ? (P p) => enhanced(<dynamic>[p]) : f;
   }
 
-  R Function(P0, P1) withTwo<R, P0, P1>(R Function(P0, P1) f) {
-    final R Function(List<dynamic>) enhanced = enhance<R>(f);
+  R? Function(P0, P1) withTwo<R, P0, P1>(R Function(P0, P1) f) {
+    final R? Function(List<dynamic>)? enhanced = enhance<R>(f);
     return enhanced != null ? (P0 p0, P1 p1) => enhanced(<dynamic>[p0, p1]) : f;
   }
 
-  R Function(P0, P1, P2) withThree<R, P0, P1, P2>(R Function(P0, P1, P2) f) {
-    final TypedApplyLike<R> enhanced = enhance<R>(f);
+  R? Function(P0, P1, P2) withThree<R, P0, P1, P2>(R Function(P0, P1, P2) f) {
+    final TypedApplyLike<R?>? enhanced = enhance<R>(f);
     return enhanced != null
         ? (P0 p0, P1 p1, P2 p2) => enhanced(<dynamic>[p0, p1, p2])
         : f;
   }
 
-  R Function(P0, P1, P2, P3) withFour<R, P0, P1, P2, P3>(
+  R? Function(P0, P1, P2, P3) withFour<R, P0, P1, P2, P3>(
       R Function(P0, P1, P2, P3) f) {
-    final TypedApplyLike<R> enhanced = enhance<R>(f);
+    final TypedApplyLike<R?>? enhanced = enhance<R>(f);
     return enhanced != null
         ? (P0 p0, P1 p1, P2 p2, P3 p3) => enhanced(<dynamic>[p0, p1, p2, p3])
         : f;
   }
 
-  R Function(P0, P1, P2, P3, P4) withFive<R, P0, P1, P2, P3, P4>(
-      R Function(P0, P1, P2, P3, P4) f) {
-    final TypedApplyLike<R> enhanced = enhance<R>(f);
+  R? Function(P0, P1, P2, P3, P4) withFive<R, P0, P1, P2, P3, P4>(
+      R? Function(P0, P1, P2, P3, P4) f) {
+    final TypedApplyLike<R>? enhanced = enhance<R>(f);
     return enhanced != null
         ? (P0 p0, P1 p1, P2 p2, P3 p3, P4 p4) =>
             enhanced(<dynamic>[p0, p1, p2, p3, p4])
         : f;
   }
 
-  R Function(P0, P1, P2, P3, P4, P5) withSix<R, P0, P1, P2, P3, P4, P5>(
-      R Function(P0, P1, P2, P3, P4, P5) f) {
-    final TypedApplyLike<R> enhanced = enhance<R>(f);
+  R? Function(P0, P1, P2, P3, P4, P5) withSix<R, P0, P1, P2, P3, P4, P5>(
+      R Function(P0, P1, P2, P3, P4, P5?) f) {
+    final TypedApplyLike<R?>? enhanced = enhance<R>(f);
     return enhanced != null
         ? (P0 p0, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5) =>
             enhanced(<dynamic>[p0, p1, p2, p3, p4, p5])
diff --git a/lib/src/redux_aop/common_aop/debounce.dart b/lib/src/redux_aop/common_aop/debounce.dart
index ce90c1c..21e94b3 100644
--- a/lib/src/redux_aop/common_aop/debounce.dart
+++ b/lib/src/redux_aop/common_aop/debounce.dart
@@ -8,7 +8,7 @@ ApplyLikeEnhancer debounce(int millis) {
   return (dynamic Function(List<dynamic>) functor) {
     int idGenerator = 0;
     return (List<dynamic> positionalArguments,
-        [Map<Symbol, dynamic> namedArguments]) async {
+        [Map<Symbol, dynamic>? namedArguments]) async {
       final int newId = ++idGenerator;
       await Future<void>.delayed(Duration(milliseconds: millis));
       if (newId == idGenerator) {
diff --git a/lib/src/redux_aop/common_aop/delay.dart b/lib/src/redux_aop/common_aop/delay.dart
index ea00ace..418a8e4 100644
--- a/lib/src/redux_aop/common_aop/delay.dart
+++ b/lib/src/redux_aop/common_aop/delay.dart
@@ -6,7 +6,7 @@ import '../aop.dart';
 ApplyLikeEnhancer delay(int millis) {
   return (dynamic Function(List<dynamic>) functor) {
     return (List<dynamic> positionalArguments,
-        [Map<Symbol, dynamic> namedArguments]) async {
+        [Map<Symbol, dynamic>? namedArguments]) async {
       await Future<void>.delayed(Duration(milliseconds: millis));
       return functor(positionalArguments);
     };
diff --git a/lib/src/redux_aop/common_aop/log.dart b/lib/src/redux_aop/common_aop/log.dart
index a5326f3..af0b622 100644
--- a/lib/src/redux_aop/common_aop/log.dart
+++ b/lib/src/redux_aop/common_aop/log.dart
@@ -8,14 +8,14 @@ ApplyLikeEnhancer logAOP(String tag) {
   return isDebug()
       ? (dynamic Function(List<dynamic>) functor) {
           return (List<dynamic> positionalArguments,
-              [Map<Symbol, dynamic> namedArguments]) {
+              [Map<Symbol, dynamic>? namedArguments]) {
             print('$tag input: $positionalArguments');
             final Object result = functor(positionalArguments);
             if (result is Future) {
-              result.then((Object r) {
+              result.then<dynamic>((Object r) {
                 print('$tag output <Future>: $r');
                 return r;
-              });
+              } as FutureOr<dynamic> Function(dynamic));
             } else {
               print('$tag output: $result');
             }
diff --git a/lib/src/redux_aop/common_aop/memoize.dart b/lib/src/redux_aop/common_aop/memoize.dart
index 898df37..ee6a104 100644
--- a/lib/src/redux_aop/common_aop/memoize.dart
+++ b/lib/src/redux_aop/common_aop/memoize.dart
@@ -1,6 +1,6 @@
 import '../aop.dart';
 
-bool _listEquals<E>(List<E> list1, List<E> list2) {
+bool _listEquals<E>(List<E> list1, List<E>? list2) {
   if (identical(list1, list2)) {
     return true;
   }
@@ -22,12 +22,12 @@ bool _listEquals<E>(List<E> list1, List<E> list2) {
 /// memoize returns cached result of function call when inputs were not changed from previous invocation.
 ApplyLikeEnhancer memoize() {
   return (dynamic Function(List<dynamic>) functor) {
-    List<dynamic> memoizeArguments;
+    List<dynamic>? memoizeArguments;
     dynamic memoizeResult;
     bool hasBeenCalled = false;
 
     return (List<dynamic> positionalArguments,
-        [Map<Symbol, dynamic> namedArguments]) {
+        [Map<Symbol, dynamic>? namedArguments]) {
       if (!hasBeenCalled ||
           !_listEquals<dynamic>(positionalArguments, memoizeArguments)) {
         memoizeResult = functor(positionalArguments);
diff --git a/lib/src/redux_aop/common_aop/performance.dart b/lib/src/redux_aop/common_aop/performance.dart
index 2dc2039..d87694e 100644
--- a/lib/src/redux_aop/common_aop/performance.dart
+++ b/lib/src/redux_aop/common_aop/performance.dart
@@ -10,15 +10,15 @@ ApplyLikeEnhancer performanceAOP(String tag) {
   return isDebug()
       ? (dynamic Function(List<dynamic>) functor) {
           return (List<dynamic> positionalArguments,
-              [Map<Symbol, dynamic> namedArguments]) {
+              [Map<Symbol, dynamic>? namedArguments]) {
             final int marked = DateTime.now().microsecondsSinceEpoch;
             final Object result = functor(positionalArguments);
             if (result is Future) {
-              result.then((Object r) {
+              result.then<dynamic>((Object r) {
                 print(
                     '$tag performance <Future>: ${_microSecsSinceEpoch() - marked}');
                 return r;
-              });
+              } as FutureOr<dynamic> Function(dynamic));
             } else {
               print('$tag performance: ${_microSecsSinceEpoch() - marked}');
             }
diff --git a/lib/src/redux_aop/common_aop/throttle.dart b/lib/src/redux_aop/common_aop/throttle.dart
index 61b928b..8b0f81d 100644
--- a/lib/src/redux_aop/common_aop/throttle.dart
+++ b/lib/src/redux_aop/common_aop/throttle.dart
@@ -8,7 +8,7 @@ ApplyLikeEnhancer throttle(int millis) {
   return (dynamic Function(List<dynamic>) functor) {
     int last = 0;
     return (List<dynamic> positionalArguments,
-        [Map<Symbol, dynamic> namedArguments]) {
+        [Map<Symbol, dynamic>? namedArguments]) {
       final int now = _microSecsSinceEpoch();
       final int elapsed = now - last;
       if (elapsed >= millis) {
diff --git a/lib/src/redux_aop/common_aop/wait_until.dart b/lib/src/redux_aop/common_aop/wait_until.dart
index 86b84a0..105ea10 100644
--- a/lib/src/redux_aop/common_aop/wait_until.dart
+++ b/lib/src/redux_aop/common_aop/wait_until.dart
@@ -6,11 +6,11 @@ ApplyLikeEnhancer waitUntil() {
   return (dynamic Function(List<dynamic>) functor) {
     bool isLocked = false;
     return (List<dynamic> positionalArguments,
-        [Map<Symbol, dynamic> namedArguments]) {
+        [Map<Symbol, dynamic>? namedArguments]) {
       if (isLocked) {
         return null;
       } else {
-        final Object result = functor(positionalArguments);
+        final Object? result = functor(positionalArguments);
         if (result is Future) {
           isLocked = true;
           return result.whenComplete(() {
diff --git a/lib/src/redux_component/auto_dispose.dart b/lib/src/redux_component/auto_dispose.dart
index 7e53fde..9383ad4 100644
--- a/lib/src/redux_component/auto_dispose.dart
+++ b/lib/src/redux_component/auto_dispose.dart
@@ -1,8 +1,11 @@
 class _Fields {
   bool isDisposed = false;
-  Set<AutoDispose> children;
-  AutoDispose parent;
-  void Function() onDisposed;
+  /// 可空
+  Set<AutoDispose>? children;
+  /// 可空
+  AutoDispose? parent;
+  /// 可空
+  void Function()? onDisposed;
 }
 
 /// Ultra-lightweight lifecycle management system
@@ -22,7 +25,7 @@ class AutoDispose {
   void dispose() {
     /// dispose all children
     if (_fields.children != null) {
-      final List<AutoDispose> copy = _fields.children.toList(growable: false);
+      final List<AutoDispose> copy = _fields.children!.toList(growable: false);
       for (AutoDispose child in copy) {
         child.dispose();
       }
@@ -41,7 +44,8 @@ class AutoDispose {
     _fields.isDisposed = true;
   }
 
-  void onDisposed(void Function() onDisposed) {
+  /// 可空 onDisposed?
+  void onDisposed(void Function()? onDisposed) {
     assert(_fields.onDisposed == null);
     if (_fields.isDisposed) {
       onDisposed?.call();
@@ -50,10 +54,11 @@ class AutoDispose {
     }
   }
 
-  void setParent(AutoDispose newParent) {
+  /// 可空 newParent？
+  void setParent(AutoDispose? newParent) {
     assert(newParent != this);
 
-    final AutoDispose oldParent = _fields.parent;
+    final AutoDispose? oldParent = _fields.parent;
     if (oldParent == newParent || isDisposed) {
       return;
     }
@@ -65,15 +70,15 @@ class AutoDispose {
 
     if (newParent != null) {
       newParent._fields.children ??= <AutoDispose>{};
-      newParent._fields.children.add(this);
+      newParent._fields.children!.add(this);
     }
     if (oldParent != null) {
-      oldParent._fields.children.remove(this);
+      oldParent._fields.children!.remove(this);
     }
     _fields.parent = newParent;
   }
 
-  AutoDispose registerOnDisposed(void Function() onDisposed) => AutoDispose()
+  AutoDispose registerOnDisposed(void Function()? onDisposed) => AutoDispose()
     ..setParent(this)
     ..onDisposed(onDisposed);
 }
diff --git a/lib/src/redux_component/basic.dart b/lib/src/redux_component/basic.dart
index 2afee28..c8f1010 100644
--- a/lib/src/redux_component/basic.dart
+++ b/lib/src/redux_component/basic.dart
@@ -17,7 +17,8 @@ typedef ViewBuilder<T> = Widget Function(
 /// Many small listAdapters could be merged to a bigger one.
 class ListAdapter {
   final int itemCount;
-  final IndexedWidgetBuilder itemBuilder;
+  /// 可空
+  final IndexedWidgetBuilder? itemBuilder;
   const ListAdapter(this.itemBuilder, this.itemCount);
 }
 
@@ -113,20 +114,23 @@ typedef EffectMiddleware<T> = Composable<Effect<dynamic>> Function(
 
 /// AOP in page on store, view, adapter, effect...
 abstract class Enhancer<T> {
-  ViewBuilder<K> viewEnhance<K>(
-    ViewBuilder<K> view,
+  ViewBuilder<K>? viewEnhance<K>(
+      /// 可空 【component.dart#98】
+    ViewBuilder<K>? view,
     AbstractComponent<K> component,
     Store<T> store,
   );
 
-  AdapterBuilder<K> adapterEnhance<K>(
-    AdapterBuilder<K> adapterBuilder,
+  /// 可空
+  AdapterBuilder<K>? adapterEnhance<K>(
+    AdapterBuilder<K>? adapterBuilder,
     AbstractAdapter<K> logic,
     Store<T> store,
   );
 
-  Effect<K> effectEnhance<K>(
-    Effect<K> effect,
+  /// 可空
+  Effect<K>? effectEnhance<K>(
+    Effect<K>? effect,
     AbstractLogic<K> logic,
     Store<T> store,
   );
@@ -134,17 +138,17 @@ abstract class Enhancer<T> {
   StoreCreator<T> storeEnhance(StoreCreator<T> creator);
 
   void unshift({
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>>? viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   });
 
   void append({
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>>? viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   });
 }
 
@@ -158,7 +162,8 @@ abstract class ExtraData {
 /// Seen in view-part or adapter-part
 abstract class ViewService implements ExtraData {
   /// The way to build adapter which is configured in Dependencies.list
-  ListAdapter buildAdapter();
+  /// 可空
+  ListAdapter? buildAdapter();
 
   /// The way to build slot component which is configured in Dependencies.slots
   Widget buildComponent(String name, {Widget defaultWidget});
@@ -201,7 +206,7 @@ abstract class Context<T> extends AutoDispose implements ExtraData {
   ///    final TickerProvider tickerProvider = context.stfState;
   ///    AnimationController controller = AnimationController(vsync: tickerProvider);
   ///    context.dispatch(ActionCreator.createController(controller));
-  State get stfState;
+  State? get stfState;
 
   /// The way to build slot component which is configured in Dependencies.slots
   /// such as custom mask or dialog
@@ -220,8 +225,8 @@ abstract class Context<T> extends AutoDispose implements ExtraData {
 
   /// listen on the changes of some parts of <T>.
   void Function() listen({
-    bool Function(T, T) isChanged,
-    void Function() onChange,
+    bool Function(T?, T?)? isChanged,
+    void Function()? onChange,
   });
 }
 
@@ -234,34 +239,35 @@ abstract class ContextSys<T> extends Context<T> implements ViewService {
 
   Store<dynamic> get store;
 
-  Enhancer<dynamic> get enhancer;
+  Enhancer<dynamic>? get enhancer;
 
-  DispatchBus get bus;
+  DispatchBus? get bus;
 }
 
 abstract class AbstractAdapterBuilder<T> {
-  ListAdapter buildAdapter(ContextSys<T> ctx);
+  /// 可空，
+  ListAdapter? buildAdapter(ContextSys<T> ctx);
 }
 
 /// Representation of each dependency
 abstract class Dependent<T> implements AbstractAdapterBuilder<Object> {
-  Get<Object> subGetter(Get<T> getter);
+  Get<dynamic> subGetter(Get<T> getter);
 
-  SubReducer<T> createSubReducer();
+  SubReducer<T>? createSubReducer();
 
   Widget buildComponent(
     Store<Object> store,
     Get<T> getter, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   });
 
   ContextSys<Object> createContext(
     Store<Object> store,
     BuildContext buildContext,
     Get<T> getState, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   });
 
   bool isComponent();
@@ -275,7 +281,8 @@ abstract class Dependent<T> implements AbstractAdapterBuilder<Object> {
 /// The logic is divided into two parts, Reducer & SideEffect.
 abstract class AbstractLogic<T> {
   /// To create a reducer<T>
-  Reducer<T> createReducer();
+  /// 可空 【helper.dart#62】
+  Reducer<T>? createReducer();
 
   /// To solve Reducer<Object> is neither a subtype nor a supertype of Reducer<T> issue.
   Object onReducer(Object state, Action action);
@@ -289,7 +296,7 @@ abstract class AbstractLogic<T> {
   /// To create each instance's dispatch
   /// Dispatch is the most important api for users which is provided by framework
   Dispatch createDispatch(
-    Dispatch effectDispatch,
+    Dispatch? effectDispatch,
     Dispatch nextDispatch,
     ContextSys<T> ctx,
   );
@@ -299,18 +306,18 @@ abstract class AbstractLogic<T> {
     Store<Object> store,
     BuildContext buildContext,
     Get<T> getState, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   });
 
   /// To create each instance's key (for recycle) if needed
-  Object key(T state);
+  Object? key(T state);
 
   /// Find a dependent by name
-  Dependent<T> slot(String name);
+  Dependent<T>? slot(String name);
 
   /// Get a adapter-dependent
-  Dependent<T> adapterDep();
+  Dependent<T>? adapterDep();
 
   Type get propertyType;
 }
@@ -320,13 +327,12 @@ abstract class AbstractComponent<T> implements AbstractLogic<T> {
   Widget buildComponent(
     Store<Object> store,
     Get<T> getter, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   });
 }
 
-abstract class AbstractAdapter<T>
-    implements AbstractLogic<T>, AbstractAdapterBuilder<T> {}
+abstract class AbstractAdapter<T> implements AbstractLogic<T>, AbstractAdapterBuilder<T> {}
 
 /// Because a main reducer will be very complicated with multiple level's state.
 /// When a reducer is slow to handle an action, maybe we should use ReducerFilter to improve the performance.
@@ -348,9 +354,11 @@ abstract class DispatchBus {
 
   void detach();
 
-  void dispatch(Action action, {Dispatch excluded});
+  /// 可空 【context.dart#122】
+  void dispatch(Action action, {Dispatch? excluded});
 
   void broadcast(Action action, {DispatchBus excluded});
 
-  void Function() registerReceiver(Dispatch dispatch);
+  /// 可空 【dispatch_bus.dart#41】
+  void Function()? registerReceiver(Dispatch dispatch);
 }
diff --git a/lib/src/redux_component/batch_store.dart b/lib/src/redux_component/batch_store.dart
index 4b9f5c2..eeb2648 100644
--- a/lib/src/redux_component/batch_store.dart
+++ b/lib/src/redux_component/batch_store.dart
@@ -10,7 +10,8 @@ mixin _BatchNotify<T> on Store<T> {
   final List<void Function()> _listeners = <void Function()>[];
   bool _isBatching = false;
   bool _isSetupBatch = false;
-  T _prevState;
+  /// 可空 【identical.dart#8】
+  T? _prevState;
 
   void setupBatch() {
     if (!_isSetupBatch) {
@@ -29,17 +30,17 @@ mixin _BatchNotify<T> on Store<T> {
 
   bool isInSuitablePhase() {
     return SchedulerBinding.instance != null &&
-        SchedulerBinding.instance.schedulerPhase !=
+        SchedulerBinding.instance?.schedulerPhase !=
             SchedulerPhase.persistentCallbacks &&
-        !(SchedulerBinding.instance.schedulerPhase == SchedulerPhase.idle &&
-            WidgetsBinding.instance.renderViewElement == null);
+        !(SchedulerBinding.instance?.schedulerPhase == SchedulerPhase.idle &&
+            WidgetsBinding.instance?.renderViewElement == null);
   }
 
   void _batch() {
     if (!isInSuitablePhase()) {
       if (!_isBatching) {
         _isBatching = true;
-        SchedulerBinding.instance.addPostFrameCallback((Duration duration) {
+        SchedulerBinding.instance?.addPostFrameCallback((Duration duration) {
           if (_isBatching) {
             _batch();
           }
@@ -78,8 +79,10 @@ class _BatchStore<T> extends Store<T> with _BatchNotify<T> {
 
 Store<T> createBatchStore<T>(
   T preloadedState,
-  Reducer<T> reducer, {
-  StoreEnhancer<T> storeEnhancer,
+  /// 可空
+  Reducer<T>? reducer, {
+  /// 可空
+  StoreEnhancer<T>? storeEnhancer,
 }) =>
     _BatchStore<T>(
       createStore(
@@ -94,7 +97,8 @@ Store<T> createBatchStore<T>(
 enum _UpdateState { Assign }
 
 // replace current state
-Reducer<T> _appendUpdateStateReducer<T>(Reducer<T> reducer) =>
+/// 可空 reducer？
+Reducer<T> _appendUpdateStateReducer<T>(Reducer<T>? reducer) =>
     (T state, Action action) => action.type == _UpdateState.Assign
         ? action.payload
         : reducer == null ? state : reducer(state, action);
@@ -112,7 +116,7 @@ Store<T> connectStores<T, K>(
     }
   };
 
-  final void Function() unsubscribe = extraStore.subscribe(subscriber);
+  final void Function()? unsubscribe = extraStore.subscribe(subscriber);
 
   /// should triggle once
   subscriber();
diff --git a/lib/src/redux_component/component.dart b/lib/src/redux_component/component.dart
index 368bf8e..744c132 100644
--- a/lib/src/redux_component/component.dart
+++ b/lib/src/redux_component/component.dart
@@ -13,31 +13,37 @@ typedef WidgetWrapper = Widget Function(Widget child);
 
 @immutable
 abstract class Component<T> extends Logic<T> implements AbstractComponent<T> {
-  final ViewBuilder<T> _view;
+  /// 可空 #47
+  final ViewBuilder<T>? _view;
   final ShouldUpdate<T> _shouldUpdate;
   final WidgetWrapper _wrapper;
   final bool _clearOnDependenciesChanged;
 
-  ViewBuilder<T> get protectedView => _view;
+  /// 可空 #16
+  ViewBuilder<T>? get protectedView => _view;
   ShouldUpdate<T> get protectedShouldUpdate => _shouldUpdate;
   WidgetWrapper get protectedWrapper => _wrapper;
   bool get protectedClearOnDependenciesChanged => _clearOnDependenciesChanged;
 
+  /// 可空 【component_extensions.dart#14】 view？ reducer? effect?
   Component({
-    @required ViewBuilder<T> view,
-    Reducer<T> reducer,
-    ReducerFilter<T> filter,
-    Effect<T> effect,
-    Dependencies<T> dependencies,
-    ShouldUpdate<T> shouldUpdate,
-    WidgetWrapper wrapper,
+    /// 可空
+    @required ViewBuilder<T>? view,
+    /// 可空
+    Reducer<T>? reducer,
+    ReducerFilter<T>? filter,
+    /// 可空
+    Effect<T>? effect,
+    Dependencies<T>? dependencies,
+    ShouldUpdate<T>? shouldUpdate,
+    WidgetWrapper? wrapper,
 
     /// implement [StateKey] in T instead of using key in Logic.
     /// class T implements StateKey {
     ///   Object _key = UniqueKey();
     ///   Object key() => _key;
     /// }
-    @deprecated Key Function(T) key,
+    @deprecated  Key Function(T)? key,
     bool clearOnDependenciesChanged = false,
   })  : _view = view,
         _wrapper = wrapper ?? _wrapperByDefault,
@@ -55,9 +61,9 @@ abstract class Component<T> extends Logic<T> implements AbstractComponent<T> {
   @override
   Widget buildComponent(
     Store<Object> store,
-    Get<Object> getter, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    Get<T> getter, {
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   }) {
     /// Check bus: DispatchBusDefault(); enhancer: EnhancerDefault<Object>();
     assert(bus != null && enhancer != null);
@@ -67,7 +73,7 @@ abstract class Component<T> extends Logic<T> implements AbstractComponent<T> {
         component: this,
         getter: asGetter<T>(getter),
         store: store,
-        key: key(getter()),
+        key: key(getter() as T) as Key,
         bus: bus,
         enhancer: enhancer,
       ),
@@ -79,9 +85,9 @@ abstract class Component<T> extends Logic<T> implements AbstractComponent<T> {
     Store<Object> store,
     BuildContext buildContext,
     Get<T> getState, {
-    @required void Function() markNeedsBuild,
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+     void Function()? markNeedsBuild,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   }) {
     assert(bus != null && enhancer != null);
     return ComponentContext<T>(
@@ -89,7 +95,7 @@ abstract class Component<T> extends Logic<T> implements AbstractComponent<T> {
       store: store,
       buildContext: buildContext,
       getState: getState,
-      view: enhancer.viewEnhance(protectedView, this, store),
+      view: enhancer.viewEnhance(protectedView, this, store)!,
       shouldUpdate: protectedShouldUpdate,
       name: name,
       markNeedsBuild: markNeedsBuild,
@@ -114,7 +120,7 @@ abstract class Component<T> extends Logic<T> implements AbstractComponent<T> {
   static ShouldUpdate<K> alwaysUpdate<K>() => (K _, K __) => true;
 
   static ShouldUpdate<K> updateByDefault<K>() =>
-      (K _, K __) => !identical(_, __);
+      (K a, K b) => !identical(a, b);
 
   static Widget _wrapperByDefault(Widget child) => child;
 }
@@ -123,16 +129,20 @@ class ComponentWidget<T> extends StatefulWidget {
   final Component<T> component;
   final Store<Object> store;
   final Get<T> getter;
+  /// 可空
   final DispatchBus bus;
+  /// 可空
   final Enhancer<Object> enhancer;
 
   const ComponentWidget({
-    @required this.component,
-    @required this.store,
-    @required this.getter,
-    this.bus,
-    this.enhancer,
-    Key key,
+    required this.component,
+    required this.store,
+    required this.getter,
+    ///todo（不确定）
+    required this.bus,
+    ///todo（不确定）
+    required this.enhancer,
+    Key? key,
   })  : assert(component != null),
         assert(store != null),
         assert(getter != null),
@@ -143,7 +153,7 @@ class ComponentWidget<T> extends StatefulWidget {
 }
 
 class ComponentState<T> extends State<ComponentWidget<T>> {
-  ComponentContext<T> _ctx;
+  late ComponentContext<T> _ctx;
 
   ComponentContext<T> get ctx => _ctx;
 
diff --git a/lib/src/redux_component/context.dart b/lib/src/redux_component/context.dart
index 37edb37..9c761a0 100644
--- a/lib/src/redux_component/context.dart
+++ b/lib/src/redux_component/context.dart
@@ -6,7 +6,8 @@ import 'basic.dart';
 import 'lifecycle.dart';
 
 mixin _ExtraMixin {
-  Map<String, Object> _extra;
+  Map<String, Object>? _extra;
+
   Map<String, Object> get extra => _extra ??= <String, Object>{};
 }
 
@@ -23,21 +24,21 @@ abstract class LogicContext<T> extends ContextSys<T> with _ExtraMixin {
 
   final Get<T> getState;
 
-  void Function() _forceUpdate;
+  void Function()? _forceUpdate;
 
   BuildContext _buildContext;
-  Dispatch _dispatch;
-  Dispatch _effectDispatch;
+  late Dispatch _dispatch;
+  late Dispatch _effectDispatch;
 
   LogicContext({
-    @required this.logic,
-    @required this.store,
-    @required BuildContext buildContext,
-    @required this.getState,
+    required this.logic,
+    required this.store,
+    required BuildContext buildContext,
+    required this.getState,
 
     /// pageBus
-    @required this.bus,
-    @required this.enhancer,
+    required this.bus,
+    required this.enhancer,
   })  : assert(logic != null),
         assert(store != null),
         assert(buildContext != null),
@@ -71,17 +72,16 @@ abstract class LogicContext<T> extends ContextSys<T> with _ExtraMixin {
   BuildContext get context => _buildContext;
 
   @override
-  T get state => getState();
+  T get state => getState.call();
 
   @override
   dynamic dispatch(Action action) => _dispatch(action);
 
   @override
-  Widget buildComponent(String name, {Widget defaultWidget}) {
+  Widget buildComponent(String name, {Widget? defaultWidget}) {
     assert(name != null, 'The name must be NotNull for buildComponent.');
-    final Dependent<T> dependent = logic.slot(name);
-    final Widget result = dependent?.buildComponent(store, getState,
-        bus: bus, enhancer: enhancer);
+    final Dependent<T>? dependent = logic.slot(name);
+    final Widget? result = dependent?.buildComponent(store, getState, bus: bus, enhancer: enhancer);
     assert(result != null || defaultWidget != null,
         'Could not found component by name "$name." You can set a default widget for buildComponent');
     return result ?? (defaultWidget ?? Container());
@@ -96,30 +96,29 @@ abstract class LogicContext<T> extends ContextSys<T> with _ExtraMixin {
   @override
   void dispose() {
     super.dispose();
-    _buildContext = null;
     _forceUpdate = null;
   }
 
   bool _throwIfDisposed() {
     if (isDisposed) {
-      throw Exception(
-          'Ctx has been disposed which could not been used any more.');
+      throw Exception('Ctx has been disposed which could not been used any more.');
     }
     return true;
   }
 
+  /// 可空
   @override
-  State<StatefulWidget> get stfState {
+  State<StatefulWidget>? get stfState {
     assert(_buildContext is StatefulElement);
     if (_buildContext is StatefulElement) {
-      final StatefulElement stfElement = _buildContext;
+      final StatefulElement stfElement = _buildContext as StatefulElement;
       return stfElement.state;
     }
     return null;
   }
 
   @override
-  void broadcastEffect(Action action, {bool excluded}) =>
+  void broadcastEffect(Action action, {bool? excluded}) =>
       bus.dispatch(action, excluded: excluded == true ? _effectDispatch : null);
 
   @override
@@ -139,12 +138,13 @@ abstract class LogicContext<T> extends ContextSys<T> with _ExtraMixin {
 
   @override
   void Function() listen({
-    bool Function(T, T) isChanged,
-    @required void Function() onChange,
+    /// 可空 #151
+    bool Function(T?, T?)? isChanged,
+     void Function()? onChange,
   }) {
     assert(onChange != null);
-    T oldState;
-    final AutoDispose disposable = registerOnDisposed(
+    T? oldState;
+    final AutoDispose? disposable = registerOnDisposed(
       store.subscribe(
         () => () {
           final T newState = state;
@@ -153,7 +153,7 @@ abstract class LogicContext<T> extends ContextSys<T> with _ExtraMixin {
               : isChanged(oldState, newState);
           oldState = newState;
           if (flag) {
-            onChange();
+            onChange?.call();
           }
         },
       ),
@@ -167,24 +167,24 @@ class ComponentContext<T> extends LogicContext<T> implements ViewUpdater<T> {
   final ViewBuilder<T> view;
   final ShouldUpdate<T> shouldUpdate;
   final String name;
-  final Function() markNeedsBuild;
-  final ContextSys<Object> sidecarCtx;
-
-  Widget _widgetCache;
-  T _latestState;
+  final Function()? markNeedsBuild;
+  final ContextSys<Object>? sidecarCtx;
+  /// 可空
+  Widget? _widgetCache;
+  late T _latestState;
 
   ComponentContext({
-    @required AbstractComponent<T> logic,
-    @required Store<Object> store,
-    @required BuildContext buildContext,
-    @required Get<T> getState,
-    @required this.view,
-    @required this.shouldUpdate,
-    @required this.name,
-    @required this.markNeedsBuild,
-    @required this.sidecarCtx,
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required AbstractComponent<T> logic,
+    required Store<Object> store,
+    required BuildContext buildContext,
+    required Get<T> getState,
+    required this.view,
+    required this.shouldUpdate,
+    required this.name,
+     this.markNeedsBuild,
+    required this.sidecarCtx,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   })  : assert(bus != null && enhancer != null),
         super(
           logic: logic,
@@ -208,13 +208,13 @@ class ComponentContext<T> extends LogicContext<T> implements ViewUpdater<T> {
   @override
   ListAdapter buildAdapter() {
     assert(sidecarCtx != null);
-    return logic.adapterDep()?.buildAdapter(sidecarCtx) ??
+    return logic.adapterDep()?.buildAdapter(sidecarCtx!) ??
         const ListAdapter(null, 0);
   }
 
   @override
   Widget buildWidget() {
-    Widget result = _widgetCache;
+    Widget? result = _widgetCache;
     if (result == null) {
       result = _widgetCache = view(state, dispatch, this);
 
@@ -238,7 +238,7 @@ class ComponentContext<T> extends LogicContext<T> implements ViewUpdater<T> {
     if (shouldUpdate(_latestState, now)) {
       _widgetCache = null;
 
-      markNeedsBuild();
+      markNeedsBuild?.call();
 
       _latestState = now;
     }
@@ -254,7 +254,7 @@ class ComponentContext<T> extends LogicContext<T> implements ViewUpdater<T> {
     _widgetCache = null;
 
     try {
-      markNeedsBuild();
+      markNeedsBuild?.call();
     } catch (e) {
       /// TODO
       /// should try-catch in force mode which is called from outside
@@ -274,14 +274,14 @@ class PureViewViewService implements ViewService {
   void broadcast(Action action) => bus.broadcast(action);
 
   @override
-  void broadcastEffect(Action action, {bool excluded}) => bus.dispatch(action);
+  void broadcastEffect(Action action, {bool? excluded}) => bus.dispatch(action);
 
   @override
   ListAdapter buildAdapter() => throw Exception(
       'Unexpected call of "buildAdapter" in a PureViewComponent');
 
   @override
-  Widget buildComponent(String name, {Widget defaultWidget}) => throw Exception(
+  Widget buildComponent(String name, {Widget? defaultWidget}) => throw Exception(
       'Unexpected call of "buildComponent" in a PureViewComponent');
 
   @override
diff --git a/lib/src/redux_component/dependencies.dart b/lib/src/redux_component/dependencies.dart
index ee0df46..f2f4dbc 100644
--- a/lib/src/redux_component/dependencies.dart
+++ b/lib/src/redux_component/dependencies.dart
@@ -2,8 +2,10 @@ import '../redux/redux.dart';
 import 'basic.dart';
 
 class Dependencies<T> {
-  final Map<String, Dependent<T>> slots;
-  final Dependent<T> adapter;
+  /// 可空
+  final Map<String, Dependent<T>>? slots;
+  /// 可空
+  final Dependent<T>? adapter;
 
   /// Use [adapter: NoneConn<T>() + Adapter<T>()] instead of [adapter: Adapter<T>()],
   /// Which is better reusability and consistency.
@@ -13,24 +15,32 @@ class Dependencies<T> {
   }) : assert(adapter == null || adapter.isAdapter(),
             'The dependent must contains adapter.');
 
-  Reducer<T> createReducer() {
-    final List<SubReducer<T>> subs = <SubReducer<T>>[];
-    if (slots != null && slots.isNotEmpty) {
-      subs.addAll(slots.entries.map<SubReducer<T>>(
+  /// 可空 combine_reducers.dart#32
+  Reducer<T>? createReducer() {
+    final List<SubReducer<T>?> subs = <SubReducer<T>?>[];
+    if (slots != null && slots?.isNotEmpty == true) {
+      subs.addAll(slots!.entries.map<SubReducer<T>?>(
         (MapEntry<String, Dependent<T>> entry) =>
             entry.value.createSubReducer(),
       ));
     }
 
     if (adapter != null) {
-      subs.add(adapter.createSubReducer());
+      subs.add(adapter?.createSubReducer());
     }
 
-    return combineReducers(<Reducer<T>>[combineSubReducers(subs)]);
+    return combineReducers(<Reducer<T>?>[combineSubReducers(subs)]);
   }
 
-  Dependent<T> slot(String type) => slots[type];
+  /// 可空
+  Dependent<T>? slot(String type) {
+    if(slots != null && slots?.isNotEmpty == true){
+      return slots![type];
+    }
+    return null;
+  }
 
-  Dependencies<T> trim() =>
+  /// 可空
+  Dependencies<T>? trim() =>
       adapter != null || slots?.isNotEmpty == true ? this : null;
 }
diff --git a/lib/src/redux_component/dependent.dart b/lib/src/redux_component/dependent.dart
index 7e8fd36..ad64cf8 100644
--- a/lib/src/redux_component/dependent.dart
+++ b/lib/src/redux_component/dependent.dart
@@ -7,64 +7,69 @@ import 'basic.dart';
 class _Dependent<T, P> implements Dependent<T> {
   final AbstractConnector<T, P> connector;
   final AbstractLogic<P> logic;
-  final SubReducer<T> subReducer;
+
+  /// 依据：[dependent.dart#21]
+  /// 可空
+  final SubReducer<T>? subReducer;
 
   _Dependent({
-    @required this.logic,
-    @required this.connector,
+    required this.logic,
+    required this.connector,
   })  : assert(logic != null),
         assert(connector != null),
-        subReducer = logic.createReducer != null
-            ? connector.subReducer(logic.createReducer())
-            : null;
+        subReducer = logic.createReducer != null ? connector.subReducer(logic.createReducer()) : null;
 
   @override
-  SubReducer<T> createSubReducer() => subReducer;
+  SubReducer<T>? createSubReducer() => subReducer;
 
   @override
   Widget buildComponent(
     Store<Object> store,
     Get<T> getter, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   }) {
     assert(bus != null && enhancer != null);
     assert(isComponent(), 'Unexpected type of ${logic.runtimeType}.');
-    final AbstractComponent<P> component = logic;
+    final AbstractComponent<P> component = logic as AbstractComponent<P>;
     return component.buildComponent(
       store,
-      () => connector.get(getter()),
+
+      /// todo(不确定)
+      () => connector.get(getter())!,
       bus: bus,
       enhancer: enhancer,
     );
   }
 
   @override
-  ListAdapter buildAdapter(covariant ContextSys<P> ctx) {
+  ListAdapter? buildAdapter(ContextSys<Object> ctx) {
     assert(isAdapter(), 'Unexpected type of ${logic.runtimeType}.');
-    final AbstractAdapter<P> adapter = logic;
-    return adapter.buildAdapter(ctx);
+    final AbstractAdapter<P> adapter = logic as dynamic;
+    return adapter.buildAdapter(ctx as dynamic);
   }
 
   @override
-  Get<P> subGetter(Get<T> getter) => () => connector.get(getter());
+  Get<P?> subGetter(Get<T> getter) {
+    return () => connector.get(getter())!;
+  }
 
   @override
-  ContextSys<P> createContext(
+  ContextSys<Object> createContext(
     Store<Object> store,
     BuildContext buildContext,
     Get<T> getState, {
-    @required DispatchBus bus,
-    @required Enhancer<Object> enhancer,
+    required DispatchBus bus,
+    required Enhancer<Object> enhancer,
   }) {
     assert(bus != null && enhancer != null);
     return logic.createContext(
       store,
       buildContext,
-      subGetter(getState),
+      subGetter(getState) as dynamic,
       bus: bus,
       enhancer: enhancer,
-    );
+    ) as ContextSys<Object>;
   }
 
   @override
@@ -78,11 +83,15 @@ class _Dependent<T, P> implements Dependent<T> {
     return Tuple3<Type, Type, Object>(
       logic.runtimeType,
       connector.runtimeType,
-      logic.key(connector.get(state)),
+
+      ///todo(不确定)
+      logic.key(connector.get(state)!),
     );
   }
 }
 
-Dependent<K> createDependent<K, T>(
-        AbstractConnector<K, T> connector, AbstractLogic<T> logic) =>
-    logic != null ? _Dependent<K, T>(connector: connector, logic: logic) : null;
+/// 可空
+Dependent<K>? createDependent<K, T>(AbstractConnector<K, T> connector, AbstractLogic<T> logic){
+  return logic != null ? _Dependent<K, T>(connector: connector, logic: logic) : null;
+}
+
diff --git a/lib/src/redux_component/dispatch_bus.dart b/lib/src/redux_component/dispatch_bus.dart
index b074a95..f12ef60 100644
--- a/lib/src/redux_component/dispatch_bus.dart
+++ b/lib/src/redux_component/dispatch_bus.dart
@@ -3,13 +3,13 @@ import 'basic.dart';
 
 class DispatchBusDefault implements DispatchBus {
   final List<Dispatch> _dispatchList = <Dispatch>[];
-  DispatchBus parent;
-  void Function() unregister;
+  DispatchBus? parent;
+  void Function()? unregister;
 
   DispatchBusDefault();
 
   @override
-  void attach(DispatchBus parent) {
+  void attach(DispatchBus? parent) {
     this.parent = parent;
     unregister?.call();
     unregister = parent?.registerReceiver(dispatch);
@@ -21,7 +21,7 @@ class DispatchBusDefault implements DispatchBus {
   }
 
   @override
-  void dispatch(Action action, {Dispatch excluded}) {
+  void dispatch(Action action, {Dispatch? excluded}) {
     final List<Dispatch> list = _dispatchList
         .where((Dispatch dispatch) => dispatch != excluded)
         .toList(growable: false);
@@ -32,12 +32,13 @@ class DispatchBusDefault implements DispatchBus {
   }
 
   @override
-  void broadcast(Action action, {DispatchBus excluded}) {
+  void broadcast(Action action, {DispatchBus? excluded}) {
     parent?.dispatch(action, excluded: excluded?.dispatch);
   }
 
+  /// 可空
   @override
-  void Function() registerReceiver(Dispatch dispatch) {
+  void Function()? registerReceiver(Dispatch? dispatch) {
     assert(!_dispatchList.contains(dispatch),
         'Do not register a dispatch which is already existed');
 
diff --git a/lib/src/redux_component/enhancer.dart b/lib/src/redux_component/enhancer.dart
index 09920db..24255b0 100644
--- a/lib/src/redux_component/enhancer.dart
+++ b/lib/src/redux_component/enhancer.dart
@@ -4,10 +4,14 @@ import '../redux/redux.dart';
 import 'basic.dart';
 
 class EnhancerDefault<T> implements Enhancer<T> {
-  StoreEnhancer<T> _storeEnhancer;
-  ViewMiddleware<T> _viewEnhancer;
-  EffectMiddleware<T> _effectEnhancer;
-  AdapterMiddleware<T> _adapterEnhancer;
+  /// 可空 #44
+  StoreEnhancer<T>? _storeEnhancer;
+  /// 可空 #51
+  ViewMiddleware<T>? _viewEnhancer;
+  /// 可空 #51
+  EffectMiddleware<T>? _effectEnhancer;
+  /// 可空 #51
+  AdapterMiddleware<T>? _adapterEnhancer;
 
   final List<Middleware<T>> _middleware = <Middleware<T>>[];
   final List<ViewMiddleware<T>> _viewMiddleware = <ViewMiddleware<T>>[];
@@ -16,10 +20,10 @@ class EnhancerDefault<T> implements Enhancer<T> {
       <AdapterMiddleware<T>>[];
 
   EnhancerDefault({
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>> ?viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   }) {
     append(
       middleware: middleware,
@@ -31,10 +35,10 @@ class EnhancerDefault<T> implements Enhancer<T> {
 
   @override
   void unshift({
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>>? viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   }) {
     if (middleware != null) {
       _middleware.insertAll(0, middleware);
@@ -56,10 +60,10 @@ class EnhancerDefault<T> implements Enhancer<T> {
 
   @override
   void append({
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>>? viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   }) {
     if (middleware != null) {
       _middleware.addAll(middleware);
@@ -79,49 +83,75 @@ class EnhancerDefault<T> implements Enhancer<T> {
     }
   }
 
+  /// 可空
   @override
-  ViewBuilder<K> viewEnhance<K>(
-    ViewBuilder<K> view,
+  ViewBuilder<K>? viewEnhance<K>(
+    ViewBuilder<K>? view,
     AbstractComponent<K> component,
     Store<T> store,
-  ) =>
-      _viewEnhancer?.call(component, store)?.call(_inverterView<K>(view)) ??
-      view;
+  ) {
+    if(view == null){
+      return null;
+    }
+    final ViewBuilder<dynamic>? viewBuilder = _inverterView<K>(view);
+    if(viewBuilder == null){
+      return view;
+    }
+    return _viewEnhancer?.call(component, store).call(viewBuilder) ?? view;
+  }
+
 
   @override
-  AdapterBuilder<K> adapterEnhance<K>(
-    AdapterBuilder<K> adapterBuilder,
+  AdapterBuilder<K>? adapterEnhance<K>(
+    AdapterBuilder<K>? adapterBuilder,
     AbstractAdapter<K> logic,
     Store<T> store,
-  ) =>
-      _adapterEnhancer
-          ?.call(logic, store)
-          ?.call(_inverterAdapter<K>(adapterBuilder)) ??
-      adapterBuilder;
+  ) {
+    if(adapterBuilder == null){
+      return null;
+    }
+    final AdapterBuilder<dynamic>? viewBuilder = _inverterAdapter<K>(adapterBuilder);
+    if(viewBuilder == null){
+      return adapterBuilder;
+    }
+    return _adapterEnhancer?.call(logic, store).call(viewBuilder) ?? adapterBuilder;
+  }
+
 
+  /// 可空
   @override
-  Effect<K> effectEnhance<K>(
-    Effect<K> effect,
+  Effect<K>? effectEnhance<K>(
+    Effect<K>? effect,
     AbstractLogic<K> logic,
     Store<T> store,
-  ) =>
-      _effectEnhancer?.call(logic, store)?.call(_inverterEffect<K>(effect)) ??
-      effect;
+  ) {
+    if(effect == null){
+      return null;
+    }
+    final Effect<dynamic>? viewBuilder = _inverterEffect<K>(effect);
+    if(viewBuilder == null){
+      return effect;
+    }
+    return _effectEnhancer?.call(logic, store).call(viewBuilder) ?? effect;
+  }
 
   @override
   StoreCreator<T> storeEnhance(StoreCreator<T> creator) =>
       _storeEnhancer?.call(creator) ?? creator;
 
-  Effect<dynamic> _inverterEffect<K>(Effect<K> effect) => effect == null
+  /// 可空
+  Effect<dynamic>? _inverterEffect<K>(Effect<K>? effect) => effect == null
       ? null
-      : (Action action, Context<dynamic> ctx) => effect(action, ctx);
+      : (Action action, Context<dynamic> ctx) => effect(action, ctx as Context<K>);
 
-  ViewBuilder<dynamic> _inverterView<K>(ViewBuilder<K> view) => view == null
+  /// 可空
+  ViewBuilder<dynamic>? _inverterView<K>(ViewBuilder<K>? view) => view == null
       ? null
       : (dynamic state, Dispatch dispatch, ViewService viewService) =>
           view(state, dispatch, viewService);
 
-  AdapterBuilder<dynamic> _inverterAdapter<K>(AdapterBuilder<K> adapter) =>
+  /// 可空
+  AdapterBuilder<dynamic>? _inverterAdapter<K>(AdapterBuilder<K>? adapter) =>
       adapter == null
           ? null
           : (dynamic state, Dispatch dispatch, ViewService viewService) =>
diff --git a/lib/src/redux_component/helper.dart b/lib/src/redux_component/helper.dart
index fa9a619..c24a314 100644
--- a/lib/src/redux_component/helper.dart
+++ b/lib/src/redux_component/helper.dart
@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:collection/collection.dart' show IterableExtension;
 import 'package:flutter/widgets.dart' hide Action, Page;
 
 import '../redux/basic.dart';
@@ -7,7 +8,7 @@ import '../utils/utils.dart';
 import 'basic.dart';
 import 'lifecycle.dart';
 
-Get<T> asGetter<T>(Get<Object> getter) {
+Get<T> asGetter<T>(Get<dynamic> getter) {
   Get<T> runtimeGetter;
   if (getter is Get<T>) {
     runtimeGetter = getter;
@@ -22,22 +23,21 @@ Get<T> asGetter<T>(Get<Object> getter) {
 
 AdapterBuilder<T> asAdapter<T>(ViewBuilder<T> view) {
   return (T unstableState, Dispatch dispatch, ViewService service) {
-    final ContextSys<T> ctx = service;
+    final ContextSys<T> ctx = service as ContextSys<T>;
     return ListAdapter(
-      (BuildContext buildContext, int index) =>
-          view(ctx.state, dispatch, service),
+      (BuildContext buildContext, int index) => view(ctx.state, dispatch, service),
       1,
     );
   };
 }
 
-Reducer<T> mergeReducers<T extends K, K>(Reducer<K> sup, [Reducer<T> sub]) {
+Reducer<T> mergeReducers<T extends K, K>(Reducer<K> sup, [Reducer<T>? sub]) {
   return (T state, Action action) {
-    return sub?.call(sup(state, action), action) ?? sup(state, action);
+    return sub?.call(sup(state, action) as T, action) ?? sup(state, action) as T;
   };
 }
 
-Effect<T> mergeEffects<T extends K, K>(Effect<K> sup, [Effect<T> sub]) {
+Effect<T> mergeEffects<T extends K, K>(Effect<K> sup, [Effect<T>? sub]) {
   return (Action action, Context<T> ctx) {
     return sub?.call(action, ctx) ?? sup.call(action, ctx);
   };
@@ -45,19 +45,28 @@ Effect<T> mergeEffects<T extends K, K>(Effect<K> sup, [Effect<T> sub]) {
 
 /// combine & as
 /// for action.type which override it's == operator
-Reducer<T> asReducer<T>(Map<Object, Reducer<T>> map) => (map == null ||
-        map.isEmpty)
-    ? null
-    : (T state, Action action) =>
-        map.entries
-            .firstWhere(
-                (MapEntry<Object, Reducer<T>> entry) =>
-                    action.type == entry.key,
-                orElse: () => null)
-            ?.value(state, action) ??
-        state;
-
-Reducer<T> filterReducer<T>(Reducer<T> reducer, ReducerFilter<T> filter) {
+Reducer<T>? asReducer<T>(Map<Object, Reducer<T>>? map) {
+  return (map == null || map.isEmpty)
+      ? null
+      : (T state, Action action) {
+          MapEntry<Object, Reducer<T>>? reducer;
+          for (MapEntry<Object, Reducer<T>> element in map.entries) {
+            if (action.type == element.key) {
+              reducer = element;
+              break;
+            }
+          }
+          // map.entries
+          //         .firstWhereOrNull((MapEntry<Object, Reducer<T>> entry) => action.type == entry.key)
+          //         ?.value(state, action) ??
+          //     state;
+
+          return reducer?.value(state, action) ?? state;
+        };
+}
+
+/// 可空 【helper.dart#62】
+Reducer<T>? filterReducer<T>(Reducer<T>? reducer, ReducerFilter<T>? filter) {
   return (reducer == null || filter == null)
       ? reducer
       : (T state, Action action) {
@@ -71,35 +80,32 @@ typedef SubEffect<T> = FutureOr<void> Function(Action action, Context<T> ctx);
 
 /// for action.type which override it's == operator
 /// return [UserEffecr]
-Effect<T> combineEffects<T>(Map<Object, SubEffect<T>> map) =>
-    (map == null || map.isEmpty)
-        ? null
-        : (Action action, Context<T> ctx) {
-            final SubEffect<T> subEffect = map.entries
-                .firstWhere(
-                  (MapEntry<Object, SubEffect<T>> entry) =>
-                      action.type == entry.key,
-                  orElse: () => null,
-                )
-                ?.value;
-
-            if (subEffect != null) {
-              return subEffect.call(action, ctx) ?? _SUB_EFFECT_RETURN_NULL;
-            }
-
-            //skip-lifecycle-actions
-            if (action.type is Lifecycle) {
-              return _SUB_EFFECT_RETURN_NULL;
-            }
-
-            /// no subEffect
-            return null;
-          };
+Effect<T>? combineEffects<T>(Map<Object, SubEffect<T>> map) => (map == null || map.isEmpty)
+    ? null
+    : (Action action, Context<T> ctx) {
+        final SubEffect<T>? subEffect = map.entries
+            .firstWhereOrNull(
+              (MapEntry<Object, SubEffect<T>> entry) => action.type == entry.key,
+            )
+            ?.value;
+
+        if (subEffect != null) {
+          return subEffect.call(action, ctx) ?? _SUB_EFFECT_RETURN_NULL;
+        }
+
+        //skip-lifecycle-actions
+        if (action.type is Lifecycle) {
+          return _SUB_EFFECT_RETURN_NULL;
+        }
+
+        /// no subEffect
+        return null;
+      };
 
 /// return [EffectDispatch]
-Dispatch createEffectDispatch<T>(Effect<T> userEffect, Context<T> ctx) {
+Dispatch createEffectDispatch<T>(Effect<T>? userEffect, Context<T> ctx) {
   return (Action action) {
-    final Object result = userEffect?.call(action, ctx);
+    final Object? result = userEffect?.call(action, ctx);
 
     //skip-lifecycle-actions
     if (action.type is Lifecycle && (result == null || result == false)) {
@@ -117,9 +123,9 @@ Dispatch createNextDispatch<T>(ContextSys<T> ctx) => (Action action) {
     };
 
 /// return [Dispatch]
-Dispatch createDispatch<T>(Dispatch onEffect, Dispatch next, Context<T> ctx) =>
-    (Action action) {
-      final Object result = onEffect?.call(action);
+/// 可空 onEffect？
+Dispatch createDispatch<T>(Dispatch? onEffect, Dispatch next, Context<T> ctx) => (Action action) {
+      final Object? result = onEffect?.call(action);
       if (result == null || result == false) {
         next(action);
       }
@@ -127,9 +133,9 @@ Dispatch createDispatch<T>(Dispatch onEffect, Dispatch next, Context<T> ctx) =>
       return result == _SUB_EFFECT_RETURN_NULL ? null : result;
     };
 
-ViewMiddleware<T> mergeViewMiddleware<T>(List<ViewMiddleware<T>> middleware) {
-  return Collections.reduce<ViewMiddleware<T>>(middleware,
-      (ViewMiddleware<T> first, ViewMiddleware<T> second) {
+/// 可空 【collections.dart#7】
+ViewMiddleware<T>? mergeViewMiddleware<T>(List<ViewMiddleware<T>> middleware) {
+  return Collections.reduce<ViewMiddleware<T>>(middleware, (ViewMiddleware<T> first, ViewMiddleware<T> second) {
     return (AbstractComponent<dynamic> component, Store<T> store) {
       final Composable<ViewBuilder<dynamic>> inner = first(component, store);
       final Composable<ViewBuilder<dynamic>> outer = second(component, store);
@@ -140,14 +146,13 @@ ViewMiddleware<T> mergeViewMiddleware<T>(List<ViewMiddleware<T>> middleware) {
   });
 }
 
-AdapterMiddleware<T> mergeAdapterMiddleware<T>(
-    List<AdapterMiddleware<T>> middleware) {
+/// 可空 【collections.dart#7】
+AdapterMiddleware<T>? mergeAdapterMiddleware<T>(List<AdapterMiddleware<T>> middleware) {
   return Collections.reduce<AdapterMiddleware<T>>(middleware,
       (AdapterMiddleware<T> first, AdapterMiddleware<T> second) {
     return (AbstractAdapter<dynamic> component, Store<T> store) {
       final Composable<AdapterBuilder<dynamic>> inner = first(component, store);
-      final Composable<AdapterBuilder<dynamic>> outer =
-          second(component, store);
+      final Composable<AdapterBuilder<dynamic>> outer = second(component, store);
       return (AdapterBuilder<dynamic> view) {
         return outer(inner(view));
       };
@@ -155,10 +160,9 @@ AdapterMiddleware<T> mergeAdapterMiddleware<T>(
   });
 }
 
-EffectMiddleware<T> mergeEffectMiddleware<T>(
-    List<EffectMiddleware<T>> middleware) {
-  return Collections.reduce<EffectMiddleware<T>>(middleware,
-      (EffectMiddleware<T> first, EffectMiddleware<T> second) {
+/// 可空 【collections.dart#7】
+EffectMiddleware<T>? mergeEffectMiddleware<T>(List<EffectMiddleware<T>> middleware) {
+  return Collections.reduce<EffectMiddleware<T>>(middleware, (EffectMiddleware<T> first, EffectMiddleware<T> second) {
     return (AbstractLogic<dynamic> logic, Store<T> store) {
       final Composable<Effect<dynamic>> inner = first(logic, store);
       final Composable<Effect<dynamic>> outer = second(logic, store);
diff --git a/lib/src/redux_component/lifecycle.dart b/lib/src/redux_component/lifecycle.dart
index 7e85b1e..eabe1de 100644
--- a/lib/src/redux_component/lifecycle.dart
+++ b/lib/src/redux_component/lifecycle.dart
@@ -34,7 +34,7 @@ enum Lifecycle {
 class LifecycleCreator {
   static Action initState() => const Action(Lifecycle.initState);
 
-  static Action build(String name) => Action(Lifecycle.build, payload: name);
+  static Action build(String? name) => Action(Lifecycle.build, payload: name);
 
   static Action reassemble() => const Action(Lifecycle.reassemble);
 
@@ -49,9 +49,9 @@ class LifecycleCreator {
 
   static Action deactivate() => const Action(Lifecycle.deactivate);
 
-  static Action appear(int index) => Action(Lifecycle.appear, payload: index);
+  static Action appear(int? index) => Action(Lifecycle.appear, payload: index);
 
-  static Action disappear(int index) =>
+  static Action disappear(int? index) =>
       Action(Lifecycle.disappear, payload: index);
 
   static Action didChangeAppLifecycleState(AppLifecycleState state) =>
diff --git a/lib/src/redux_component/local.dart b/lib/src/redux_component/local.dart
index f604d16..9160c6b 100644
--- a/lib/src/redux_component/local.dart
+++ b/lib/src/redux_component/local.dart
@@ -54,23 +54,23 @@ abstract class LocalProps<T extends LocalProps<T>> {
 @immutable
 class _LocalPropsProvider<T> {
   final T Function(Context<Object>) construct;
-  final void Function(T, Context<Object>) destruct;
+  final void Function(T, Context<Object>)? destruct;
 
-  const _LocalPropsProvider({@required this.construct, this.destruct})
+  const _LocalPropsProvider({required this.construct, this.destruct})
       : assert(construct != null,
             'Please provide a constructor to create <T> instance.');
 
-  T of(ExtraData context) {
+  T? of(ExtraData context) {
     assert(context is Context<Object>);
-    final Context<Object> ctx = context;
+    final Context<Object> ctx = context as Context<Object>;
     if (ctx.extra[_key] == null) {
       final T result = construct(ctx);
-      ctx.extra[_key] = result;
+      ctx.extra[_key] = result as Object;
       if (destruct != null) {
-        ctx.registerOnDisposed(() => destruct(result, ctx));
+        ctx.registerOnDisposed(() => destruct!(result, ctx));
       }
     }
-    return ctx.extra[_key];
+    return ctx.extra[_key] as T?;
   }
 
   String get _key => '\$ ${T.toString()}';
diff --git a/lib/src/redux_component/logic.dart b/lib/src/redux_component/logic.dart
index 006116e..e56c3e5 100644
--- a/lib/src/redux_component/logic.dart
+++ b/lib/src/redux_component/logic.dart
@@ -12,36 +12,47 @@ import 'helper.dart' as helper;
 /// 3. Dependencies
 /// 4. Key
 abstract class Logic<T> implements AbstractLogic<T> {
-  final Reducer<T> _reducer;
-  final ReducerFilter<T> _filter;
-  final Effect<T> _effect;
-  final Dependencies<T> _dependencies;
-  final Object Function(T state) _key;
+  /// 可空 【logic.dart#82】
+  final Reducer<T>? _reducer;
+  /// 可空 【logic.dart#82】
+  final ReducerFilter<T>? _filter;
+  /// 可空
+  final Effect<T>? _effect;
+  /// 可空
+  final Dependencies<T>? _dependencies;
+  final Object Function(T state)? _key;
 
   /// for extends
-  Reducer<T> get protectedReducer => _reducer;
-  ReducerFilter<T> get protectedFilter => _filter;
-  Effect<T> get protectedEffect => _effect;
-  Dependencies<T> get protectedDependencies => _dependencies;
-  Reducer<T> get protectedDependenciesReducer =>
+  /// 可空 [private_reducer_mixin.dart#12]
+  Reducer<T>? get protectedReducer => _reducer;
+  /// 可空 【logic.dart#82】
+  ReducerFilter<T>? get protectedFilter => _filter;
+  /// 可空
+  Effect<T>? get protectedEffect => _effect;
+  /// 可空 【logic.dart#82】
+  Dependencies<T>? get protectedDependencies => _dependencies;
+  Reducer<T>? get protectedDependenciesReducer =>
       protectedDependencies?.createReducer();
-  Object Function(T state) get protectedKey => _key;
+  /// 可空
+  Object Function(T state)? get protectedKey => _key;
 
   /// Used as function cache to improve operational efficiency
   final Map<String, Object> _resultCache = <String, Object>{};
 
   Logic({
-    Reducer<T> reducer,
-    Dependencies<T> dependencies,
-    ReducerFilter<T> filter,
-    Effect<T> effect,
+    /// 可空
+    Reducer<T>? reducer,
+    Dependencies<T>? dependencies,
+    ReducerFilter<T>? filter,
+    /// 可空
+    Effect<T>? effect,
 
     /// implement [StateKey] in T instead of using key in Logic.
     /// class T implements StateKey {
     ///   Object _key = UniqueKey();
     ///   Object key() => _key;
     /// }
-    @deprecated Object Function(T state) key,
+    @deprecated Object Function(T state)? key,
   })  : _reducer = reducer,
         _filter = filter,
         _effect = effect,
@@ -68,19 +79,20 @@ abstract class Logic<T> implements AbstractLogic<T> {
   /// _resultCache['key'] = null;
   /// then
   /// _resultCache.containsKey('key') will be true;
-  R cache<R>(String key, Get<R> getter) => _resultCache.containsKey(key)
-      ? _resultCache[key]
-      : (_resultCache[key] = getter());
+  R cache<R>(String? key, Get<R> getter) => _resultCache.containsKey(key)
+      ? _resultCache[key] as R
+      : (_resultCache[key!] = getter() as dynamic) as R;
 
+  /// 可空 【helper.dart#62】 protectedFilter?
   @override
-  Reducer<T> createReducer() => helper.filterReducer(
+  Reducer<T>? createReducer() => helper.filterReducer(
       combineReducers<T>(
-          <Reducer<T>>[protectedReducer, protectedDependenciesReducer]),
+          <Reducer<T>?>[protectedReducer, protectedDependenciesReducer]),
       protectedFilter);
 
   @override
   Object onReducer(Object state, Action action) =>
-      cache<Reducer<T>>('onReducer', createReducer)?.call(state, action) ??
+      cache<Reducer<T>?>('onReducer', createReducer)?.call(state as T, action) ??
       state;
 
   @override
@@ -91,7 +103,7 @@ abstract class Logic<T> implements AbstractLogic<T> {
         enhancer.effectEnhance(
           protectedEffect,
           this,
-          ctx.store,
+          ctx.store as Store<Object>,
         ),
         ctx);
   }
@@ -100,9 +112,10 @@ abstract class Logic<T> implements AbstractLogic<T> {
   Dispatch createNextDispatch(ContextSys<T> ctx, Enhancer<Object> enhancer) =>
       helper.createNextDispatch<T>(ctx);
 
+  /// 可空 effectDispatch？
   @override
   Dispatch createDispatch(
-    Dispatch effectDispatch,
+    Dispatch? effectDispatch,
     Dispatch nextDispatch,
     Context<T> ctx,
   ) =>
@@ -112,8 +125,9 @@ abstract class Logic<T> implements AbstractLogic<T> {
   Object key(T state) => _key?.call(state) ?? ValueKey<Type>(runtimeType);
 
   @override
-  Dependent<T> slot(String type) => protectedDependencies?.slot(type);
+  Dependent<T>? slot(String type) => protectedDependencies?.slot(type);
 
+  ///可空
   @override
-  Dependent<T> adapterDep() => protectedDependencies?.adapter;
+  Dependent<T>? adapterDep() => protectedDependencies?.adapter;
 }
diff --git a/lib/src/redux_component/page.dart b/lib/src/redux_component/page.dart
index 5c40c20..e1ee020 100644
--- a/lib/src/redux_component/page.dart
+++ b/lib/src/redux_component/page.dart
@@ -9,7 +9,8 @@ import 'dispatch_bus.dart';
 import 'enhancer.dart';
 
 /// init store's state by route-params
-typedef InitState<T, P> = T Function(P params);
+/// 可空 params？
+typedef InitState<T, P> = T Function(P? params);
 
 typedef StoreUpdater<T> = Store<T> Function(Store<T> store);
 
@@ -28,25 +29,25 @@ abstract class Page<T, P> extends Component<T> {
   final List<StoreUpdater<T>> _storeUpdaters = <StoreUpdater<T>>[];
 
   Page({
-    @required InitState<T, P> initState,
-    @required ViewBuilder<T> view,
-    Reducer<T> reducer,
-    ReducerFilter<T> filter,
-    Effect<T> effect,
-    Dependencies<T> dependencies,
-    ShouldUpdate<T> shouldUpdate,
-    WidgetWrapper wrapper,
+    required InitState<T, P> initState,
+    required ViewBuilder<T> view,
+    Reducer<T>? reducer,
+    ReducerFilter<T>? filter,
+    Effect<T>? effect,
+    Dependencies<T>? dependencies,
+    ShouldUpdate<T>? shouldUpdate,
+    WidgetWrapper? wrapper,
 
     /// implement [StateKey] in T instead of using key in Logic.
     /// class T implements StateKey {
     ///   Object _key = UniqueKey();
     ///   Object key() => _key;
     /// }
-    @deprecated Key Function(T) key,
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    @deprecated Key Function(T)? key,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>>? viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   })  : assert(initState != null),
         _initState = initState,
         enhancer = EnhancerDefault<T>(
@@ -67,12 +68,14 @@ abstract class Page<T, P> extends Component<T> {
           key: key,
         );
 
-  Widget buildPage(P param) => protectedWrapper(_PageWidget<T, P>(
+  /// 可空 param？
+  Widget buildPage(P? param) => protectedWrapper(_PageWidget<T, P>(
         page: this,
         param: param,
       ));
 
-  Store<T> createStore(P param) => updateStore(createBatchStore<T>(
+  /// 可空 param？
+  Store<T> createStore(P? param) => updateStore(createBatchStore<T>(
         _initState(param),
         createReducer(),
         storeEnhancer: enhancer.storeEnhance,
@@ -80,30 +83,30 @@ abstract class Page<T, P> extends Component<T> {
 
   Store<T> updateStore(Store<T> store) => _storeUpdaters.fold(
         store,
-        (Store<T> previousValue, StoreUpdater<T> element) =>
-            element(previousValue),
+        (Store<T> previousValue, StoreUpdater<T> element) => element(previousValue),
       );
 
   /// page-store connect with app-store
   void connectExtraStore<K>(
     Store<K> extraStore,
 
+        // Object pagestate, GlobalState appState
     /// To solve Reducer<Object> is neither a subtype nor a supertype of Reducer<T> issue.
     Object Function(Object, K) update,
   ) =>
       _storeUpdaters.add((Store<T> store) => connectStores<Object, K>(
-            store,
+            store as Store<Object>,
             extraStore,
             update,
-          ));
+          ) as Store<T>);
 
   DispatchBus createPageBus() => DispatchBusDefault();
 
   void unshift({
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>>? viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   }) {
     enhancer.unshift(
       middleware: middleware,
@@ -114,10 +117,10 @@ abstract class Page<T, P> extends Component<T> {
   }
 
   void append({
-    List<Middleware<T>> middleware,
-    List<ViewMiddleware<T>> viewMiddleware,
-    List<EffectMiddleware<T>> effectMiddleware,
-    List<AdapterMiddleware<T>> adapterMiddleware,
+    List<Middleware<T>>? middleware,
+    List<ViewMiddleware<T>>? viewMiddleware,
+    List<EffectMiddleware<T>>? effectMiddleware,
+    List<AdapterMiddleware<T>>? adapterMiddleware,
   }) {
     enhancer.append(
       middleware: middleware,
@@ -130,12 +133,13 @@ abstract class Page<T, P> extends Component<T> {
 
 class _PageWidget<T, P> extends StatefulWidget {
   final Page<T, P> page;
-  final P param;
+  /// 可空 【app.dart#77】
+  final P? param;
 
   const _PageWidget({
-    Key key,
-    @required this.page,
-    @required this.param,
+    Key? key,
+    required this.page,
+    this.param,
   }) : super(key: key);
 
   @override
@@ -143,8 +147,8 @@ class _PageWidget<T, P> extends StatefulWidget {
 }
 
 class _PageState<T, P> extends State<_PageWidget<T, P>> {
-  Store<T> _store;
-  DispatchBus _pageBus;
+  late Store<T> _store;
+  late DispatchBus _pageBus;
 
   final Map<String, Object> extra = <String, Object>{};
 
@@ -172,10 +176,10 @@ class _PageState<T, P> extends State<_PageWidget<T, P>> {
     // );
 
     return widget.page.buildComponent(
-      _store,
+      _store as Store<Object>,
       _store.getState,
       bus: _pageBus,
-      enhancer: widget.page.enhancer,
+      enhancer: widget.page.enhancer as Enhancer<Object>,
     );
   }
 
@@ -195,21 +199,20 @@ class PageProvider extends InheritedWidget {
   final Map<String, Object> extra;
 
   const PageProvider({
-    @required this.store,
-    @required this.extra,
-    @required Widget child,
-    Key key,
+    required this.store,
+    required this.extra,
+    required Widget child,
+    Key? key,
   })  : assert(store != null),
         assert(child != null),
         super(child: child, key: key);
 
-  static PageProvider tryOf(BuildContext context) {
-    final PageProvider provider =
-        context.dependOnInheritedWidgetOfExactType<PageProvider>();
+  /// 可空 【framework.dart#2113】
+  static PageProvider? tryOf(BuildContext context) {
+    final PageProvider? provider = context.dependOnInheritedWidgetOfExactType<PageProvider>();
     return provider;
   }
 
   @override
-  bool updateShouldNotify(PageProvider oldWidget) =>
-      store != oldWidget.store && extra != oldWidget.extra;
+  bool updateShouldNotify(PageProvider oldWidget) => store != oldWidget.store && extra != oldWidget.extra;
 }
diff --git a/lib/src/redux_component_mixin/private_reducer_mixin.dart b/lib/src/redux_component_mixin/private_reducer_mixin.dart
index 6cdf9fc..bfde711 100644
--- a/lib/src/redux_component_mixin/private_reducer_mixin.dart
+++ b/lib/src/redux_component_mixin/private_reducer_mixin.dart
@@ -8,9 +8,10 @@ import '../redux_component/redux_component.dart';
 ///   );
 /// }
 mixin PrivateReducerMixin<T> on Logic<T> {
+  /// 可空
   @override
-  Reducer<T> get protectedReducer {
-    final Reducer<T> superReducer = super.protectedReducer;
+  Reducer<T>? get protectedReducer {
+    final Reducer<T>? superReducer = super.protectedReducer;
     return superReducer != null
         ? (T state, Action action) {
             if (action is PrivateAction && action.target == state) {
@@ -22,14 +23,15 @@ mixin PrivateReducerMixin<T> on Logic<T> {
   }
 
   @override
-  Dispatch createDispatch(Dispatch effect, Dispatch next, Context<T> ctx) {
+  Dispatch createDispatch(Dispatch? effect, Dispatch next, Context<T> ctx) {
     final Dispatch superDispatch = super.createDispatch(effect, next, ctx);
     return (Action action) {
       if (action.type is! Lifecycle && action is! PrivateAction) {
         action = PrivateAction(
           action.type,
           payload: action.payload,
-          target: ctx.state,
+          ///todo（不确定）
+          target: ctx.state as Object,
         );
       }
       return superDispatch(action);
@@ -39,7 +41,7 @@ mixin PrivateReducerMixin<T> on Logic<T> {
 
 class PrivateAction extends Action {
   final Object target;
-  PrivateAction(Object type, {dynamic payload, this.target})
+  PrivateAction(Object type, {dynamic payload, required this.target})
       : super(type, payload: payload);
 
   Action asAction() => Action(type, payload: payload);
diff --git a/lib/src/redux_component_mixin/visible_change_mixin.dart b/lib/src/redux_component_mixin/visible_change_mixin.dart
index 400c92a..05843ff 100644
--- a/lib/src/redux_component_mixin/visible_change_mixin.dart
+++ b/lib/src/redux_component_mixin/visible_change_mixin.dart
@@ -13,36 +13,36 @@ import '../utils/utils.dart';
 /// }
 mixin VisibleChangeMixin<T> on AbstractAdapter<T> {
   @override
-  ListAdapter buildAdapter(ContextSys<T> ctx) {
-    return _wrapVisibleChange<T>(super.buildAdapter(ctx), ctx);
+  ListAdapter? buildAdapter(ContextSys<T> ctx) {
+    return _wrapVisibleChange<T>(super.buildAdapter(ctx), ctx as dynamic);
   }
 }
 
 class _VisibleChangeState extends State<_VisibleChangeWidget> {
   @override
   Widget build(BuildContext context) =>
-      widget.itemBuilder(context, widget.index);
+      widget.itemBuilder!(context, widget.index!);
 
   @override
   void initState() {
     super.initState();
-    widget.dispatch(LifecycleCreator.appear(widget.index));
+    widget.dispatch!(LifecycleCreator.appear(widget.index));
   }
 
   @override
   void dispose() {
-    widget.dispatch(LifecycleCreator.disappear(widget.index));
+    widget.dispatch!(LifecycleCreator.disappear(widget.index));
     super.dispose();
   }
 }
 
 class _VisibleChangeWidget extends StatefulWidget {
-  final IndexedWidgetBuilder itemBuilder;
-  final int index;
-  final Dispatch dispatch;
+  final IndexedWidgetBuilder? itemBuilder;
+  final int? index;
+  final Dispatch? dispatch;
 
   const _VisibleChangeWidget({
-    Key key,
+    Key? key,
     this.itemBuilder,
     this.index,
     this.dispatch,
@@ -52,12 +52,14 @@ class _VisibleChangeWidget extends StatefulWidget {
   State<StatefulWidget> createState() => _VisibleChangeState();
 }
 
-ListAdapter _wrapVisibleChange<T>(
-  ListAdapter listAdapter,
-  LogicContext<T> ctx,
+/// 可空
+ListAdapter? _wrapVisibleChange<T>(
+    /// 可空
+  ListAdapter? listAdapter,
+  LogicContext<T>? ctx,
 ) {
   final _VisibleChangeDispatch onChange =
-      (ctx.extra['\$visible'] ??= _VisibleChangeDispatch(ctx.dispatch));
+      (ctx?.extra['\$visible'] ??= _VisibleChangeDispatch(ctx.dispatch)) as _VisibleChangeDispatch;
 
   return listAdapter == null
       ? null
diff --git a/lib/src/redux_component_mixin/widgets_binding_observer_mixin.dart b/lib/src/redux_component_mixin/widgets_binding_observer_mixin.dart
index 0d78fe6..750c799 100644
--- a/lib/src/redux_component_mixin/widgets_binding_observer_mixin.dart
+++ b/lib/src/redux_component_mixin/widgets_binding_observer_mixin.dart
@@ -20,12 +20,12 @@ class _WidgetsBindingObserverStfState<T> extends ComponentState<T>
   @override
   void initState() {
     super.initState();
-    WidgetsBinding.instance.addObserver(this);
+    WidgetsBinding.instance!.addObserver(this);
   }
 
   @override
   void dispose() {
-    WidgetsBinding.instance.removeObserver(this);
+    WidgetsBinding.instance!.removeObserver(this);
     super.dispose();
   }
 
diff --git a/lib/src/redux_connector/connector.dart b/lib/src/redux_connector/connector.dart
index 6b81912..7095bbb 100644
--- a/lib/src/redux_connector/connector.dart
+++ b/lib/src/redux_connector/connector.dart
@@ -3,18 +3,19 @@ import '../redux/redux.dart';
 import 'op_mixin.dart';
 
 class ConnOp<T, P> extends MutableConn<T, P> with ConnOpMixin<T, P> {
-  final P Function(T) _getter;
-  final void Function(T, P) _setter;
+  final P Function(T)? _getter;
+  final void Function(T, P)? _setter;
 
   const ConnOp({
-    P Function(T) get,
-    void Function(T, P) set,
+    P Function(T)? get,
+    void Function(T, P)? set,
   })  : _getter = get,
         _setter = set;
 
+  /// 可空
   @override
-  P get(T state) => _getter(state);
+  P? get(T? state) => state != null ? _getter?.call(state) : null;
 
   @override
-  void set(T state, P subState) => _setter(state, subState);
+  void set(T state, P subState) => _setter?.call(state, subState);
 }
diff --git a/lib/src/redux_connector/helper.dart b/lib/src/redux_connector/helper.dart
index 1cf7869..9875ff7 100644
--- a/lib/src/redux_connector/helper.dart
+++ b/lib/src/redux_connector/helper.dart
@@ -7,7 +7,8 @@ class ConnHelper {
     return _AbstractConnector<T, P, K>(one, two);
   }
 
-  static Dependent<T> join<T, P>(
+  /// 可空
+  static Dependent<T>? join<T, P>(
           AbstractConnector<T, P> conn, AbstractLogic<P> logic) =>
       createDependent<T, P>(conn, logic);
 }
@@ -18,15 +19,16 @@ class _AbstractConnector<T, P, K> extends AbstractConnector<T, K> {
 
   _AbstractConnector(this.one, this.two);
 
+  /// 可空
   @override
-  K get(T state) {
+  K? get(T? state) {
     return two.get(one.get(state));
   }
 
   @override
-  SubReducer<T> subReducer(Reducer<K> reducer) {
+  SubReducer<T>? subReducer(Reducer<K>? reducer) {
     return one.subReducer((P state, Action action) {
-      return two.subReducer(reducer)(state, action, false);
+      return two.subReducer(reducer)?.call(state, action, false);
     });
   }
 }
diff --git a/lib/src/redux_connector/map_like.dart b/lib/src/redux_connector/map_like.dart
index 3c2c921..18c4a9e 100644
--- a/lib/src/redux_connector/map_like.dart
+++ b/lib/src/redux_connector/map_like.dart
@@ -6,40 +6,46 @@ abstract class MapLike {
 
   void clear() => _fieldsMap.clear();
 
-  Object operator [](String key) => _fieldsMap[key];
+  Object operator [](String key) => _fieldsMap[key]!;
 
   void operator []=(String key, Object value) => _fieldsMap[key] = value;
 
   bool containsKey(String key) => _fieldsMap.containsKey(key);
 
-  void copyFrom(MapLike from) =>
-      _fieldsMap = <String, Object>{}..addAll(from._fieldsMap);
+  void copyFrom(MapLike from) => _fieldsMap = <String, Object>{}..addAll(from._fieldsMap);
 }
 
 ConnOp<T, P> withMapLike<T extends MapLike, P>(String key) => ConnOp<T, P>(
-      get: (T state) => state[key],
-      set: (T state, P sub) => state[key] = sub,
+      get: (T state) => state[key] as P,
+      set: (T state, P sub) => state[key] = sub as Object,
     );
 
 class AutoInitConnector<T extends MapLike, P> extends ConnOp<T, P> {
   static final String Function() _gen = generator();
 
   final String _key;
-  final void Function(T state, P sub) _setHook;
+  final void Function(T state, P sub)? _setHook;
   final P Function(T state) init;
 
-  AutoInitConnector(this.init, {String key, void set(T state, P sub)})
+  AutoInitConnector(this.init, {String? key, void set(T state, P sub)?})
       : assert(init != null),
         _setHook = set,
         _key = key ?? _gen();
 
   @override
-  P get(T state) =>
-      state.containsKey(_key) ? state[_key] : (state[_key] = init(state));
+  P? get(T? state) {
+    if (state != null) {
+      if (state.containsKey(_key)) {
+        return state[_key] as P?;
+      }
+      return (state[_key] = init(state) as Object) as P?;
+    }
+    return null;
+  }
 
   @override
   void set(T state, P subState) {
-    state[_key] = subState;
+    state[_key] = subState as Object;
     _setHook?.call(state, subState);
   }
 }
diff --git a/lib/src/redux_connector/none.dart b/lib/src/redux_connector/none.dart
index aed8554..65a305c 100644
--- a/lib/src/redux_connector/none.dart
+++ b/lib/src/redux_connector/none.dart
@@ -5,7 +5,7 @@ class NoneConn<T> extends ImmutableConn<T, T> with ConnOpMixin<T, T> {
   const NoneConn();
 
   @override
-  T get(T state) => state;
+  T? get(T? state) => state;
 
   @override
   T set(T state, T subState) => subState;
diff --git a/lib/src/redux_connector/op_mixin.dart b/lib/src/redux_connector/op_mixin.dart
index 4355841..7da123d 100644
--- a/lib/src/redux_connector/op_mixin.dart
+++ b/lib/src/redux_connector/op_mixin.dart
@@ -2,6 +2,7 @@ import '../redux/redux.dart';
 import '../redux_component/redux_component.dart';
 
 mixin ConnOpMixin<T, P> on AbstractConnector<T, P> {
+  /// 可空 【dependent.dart#89】
   Dependent<T> operator +(AbstractLogic<P> logic) =>
-      createDependent<T, P>(this, logic);
+      createDependent<T, P>(this, logic)!;
 }
diff --git a/lib/src/redux_connector/reselect.dart b/lib/src/redux_connector/reselect.dart
index 9e66416..449815c 100644
--- a/lib/src/redux_connector/reselect.dart
+++ b/lib/src/redux_connector/reselect.dart
@@ -30,8 +30,8 @@ bool _listEquals(List<dynamic> list1, List<dynamic> list2) {
 
 abstract class _BasicReselect<T, P> extends MutableConn<T, P>
     with ConnOpMixin<T, P> {
-  List<dynamic> _subsCache;
-  P _pCache;
+  late List<dynamic> _subsCache;
+  late P _pCache;
   bool _hasBeenCalled = false;
 
   List<dynamic> getSubs(T state);
@@ -39,8 +39,9 @@ abstract class _BasicReselect<T, P> extends MutableConn<T, P>
   P reduceSubs(List<dynamic> list);
 
   @override
-  P get(T state) {
-    final List<dynamic> subs = getSubs(state);
+  P? get(T? state) {
+    ///todo(不确定)
+    final List<dynamic> subs = getSubs(state!);
     if (!_hasBeenCalled || !_listEquals(subs, _subsCache)) {
       _subsCache = subs;
       _pCache = reduceSubs(_subsCache);
@@ -164,8 +165,8 @@ abstract class Reselect<T, P> extends _BasicReselect<T, P> {
 
 /// issue [https://github.com/alibaba/fish-redux/issues/482]
 mixin ReselectMixin<T, P> on MutableConn<T, P> {
-  List<dynamic> _cachedFactors;
-  P _cachedResult;
+  late List<dynamic> _cachedFactors;
+  late P _cachedResult;
   bool _hasBeenCalled = false;
 
   P computed(T state);
@@ -174,8 +175,9 @@ mixin ReselectMixin<T, P> on MutableConn<T, P> {
 
   @mustCallSuper
   @override
-  P get(T state) {
-    final List<dynamic> newFactors = factors(state);
+  P? get(T? state) {
+    ///todo(不确定)
+    final List<dynamic> newFactors = factors(state!);
     if (!_hasBeenCalled || !_listEquals(newFactors, _cachedFactors)) {
       _cachedFactors = newFactors.toList(growable: false);
       _cachedResult = computed(state);
diff --git a/lib/src/redux_middleware/adapter_middleware/safety_adapter.dart b/lib/src/redux_middleware/adapter_middleware/safety_adapter.dart
index e4456ea..1b1858a 100644
--- a/lib/src/redux_middleware/adapter_middleware/safety_adapter.dart
+++ b/lib/src/redux_middleware/adapter_middleware/safety_adapter.dart
@@ -7,7 +7,7 @@ import '../../utils/utils.dart';
 /// type = {0, 1}
 AdapterMiddleware<T> safetyAdapter<T>({
   Widget Function(dynamic, StackTrace,
-          {AbstractAdapter<dynamic> adapter, Store<T> store, int type})
+          {AbstractAdapter<dynamic> adapter, Store<T> store, int type})?
       onError,
 }) {
   return (AbstractAdapter<dynamic> adapter, Store<T> store) {
@@ -19,7 +19,8 @@ AdapterMiddleware<T> safetyAdapter<T>({
                 final ListAdapter result = next(state, dispatch, viewService);
                 return ListAdapter((BuildContext buildContext, int index) {
                   try {
-                    return result.itemBuilder(buildContext, index);
+                    ///todo(不确定)
+                    return result.itemBuilder!(buildContext, index);
                   } catch (e, stackTrace) {
                     return onError?.call(
                           e,
@@ -32,7 +33,7 @@ AdapterMiddleware<T> safetyAdapter<T>({
                   }
                 }, result.itemCount);
               } catch (e, stackTrace) {
-                final Widget errorWidget = onError?.call(
+                final Widget? errorWidget = onError?.call(
                   e,
                   stackTrace,
                   adapter: adapter,
diff --git a/lib/src/redux_middleware/middleware/log.dart b/lib/src/redux_middleware/middleware/log.dart
index f6a02f1..649c70e 100644
--- a/lib/src/redux_middleware/middleware/log.dart
+++ b/lib/src/redux_middleware/middleware/log.dart
@@ -5,16 +5,17 @@ import '../../utils/utils.dart';
 /// It works on debug mode.
 Middleware<T> logMiddleware<T>({
   String tag = 'redux',
-  String Function(T) monitor,
+  /// 可空
+  String Function(T)? monitor,
 }) {
-  return ({Dispatch dispatch, Get<T> getState}) {
+  return ({ Dispatch? dispatch, Get<T>? getState}) {
     return (Dispatch next) {
       return isDebug()
           ? (Action action) {
               print('---------- [$tag] ----------');
               print('[$tag] ${action.type} ${action.payload}');
 
-              final T prevState = getState();
+              final T prevState = getState!();
               if (monitor != null) {
                 print('[$tag] prev-state: ${monitor(prevState)}');
               }
diff --git a/lib/src/redux_middleware/middleware/performance.dart b/lib/src/redux_middleware/middleware/performance.dart
index 2566f41..1c6e49e 100644
--- a/lib/src/redux_middleware/middleware/performance.dart
+++ b/lib/src/redux_middleware/middleware/performance.dart
@@ -4,7 +4,7 @@ import '../../utils/utils.dart';
 /// Middleware for print action dispatch performance by time consuming.
 /// It works on debug mode.
 Middleware<T> performanceMiddleware<T>({String tag = 'redux'}) {
-  return ({Dispatch dispatch, Get<T> getState}) {
+  return ({Dispatch? dispatch, Get<T>? getState}) {
     return (Dispatch next) {
       return isDebug()
           ? (Action action) {
diff --git a/lib/src/redux_middleware/view_middleware/safety_view.dart b/lib/src/redux_middleware/view_middleware/safety_view.dart
index 13563be..29507db 100644
--- a/lib/src/redux_middleware/view_middleware/safety_view.dart
+++ b/lib/src/redux_middleware/view_middleware/safety_view.dart
@@ -6,7 +6,7 @@ import '../../utils/utils.dart';
 
 ViewMiddleware<T> safetyView<T>(
     {Widget Function(dynamic, StackTrace,
-            {AbstractComponent<dynamic> component, Store<T> store})
+            {AbstractComponent<dynamic> component, Store<T> store})?
         onError}) {
   return (AbstractComponent<dynamic> component, Store<T> store) {
     return (ViewBuilder<dynamic> next) {
diff --git a/lib/src/redux_routes/page_routes.dart b/lib/src/redux_routes/page_routes.dart
index ba8e396..84f7a50 100644
--- a/lib/src/redux_routes/page_routes.dart
+++ b/lib/src/redux_routes/page_routes.dart
@@ -13,10 +13,10 @@ class PageRoutes implements AbstractRoutes {
   final Map<String, Page<Object, dynamic>> pages;
 
   PageRoutes({
-    @required this.pages,
+    required this.pages,
 
     /// For common enhance
-    void Function(String, Page<Object, dynamic>) visitor,
+    void Function(String, Page<Object, dynamic>)? visitor,
   }) : assert(pages != null, 'Expected the pages to be non-null value.') {
     if (visitor != null) {
       pages.forEach(visitor);
@@ -25,5 +25,5 @@ class PageRoutes implements AbstractRoutes {
 
   @override
   Widget buildPage(String path, dynamic arguments) =>
-      pages[path]?.buildPage(arguments);
+      pages[path]!.buildPage(arguments);
 }
diff --git a/lib/src/utils/collections.dart b/lib/src/utils/collections.dart
index ab05e9e..41dc349 100644
--- a/lib/src/utils/collections.dart
+++ b/lib/src/utils/collections.dart
@@ -3,10 +3,12 @@ import 'dart:core';
 /// Util for collections.
 class Collections {
   /// Wrap List.reduce with a check list is null or empty.
-  static E reduce<E>(List<E> list, E combine(E e0, E e1)) =>
+  /// 可空
+  static E? reduce<E>(List<E>? list, E combine(E e0, E e1)) =>
       (list == null || list.isEmpty) ? null : list.reduce(combine);
 
   /// Wrap List.fold with a check list is null or empty.
+  /// 可空
   static T fold<T, E>(T init, List<E> list, T combine(T e0, E e1)) =>
       (list == null || list.isEmpty) ? init : list.fold(init, combine);
 
@@ -16,16 +18,17 @@ class Collections {
   /// List<String> b = ['1', '2', '3'];
   /// List<List<String>> list = [a, b] // [[a, b, c], [1, 2, 3]]
   /// List<String> listFlatten = Collections.flatten(list) // [a, b, c, 1, 2, 3]
-  static List<E> flatten<E>(List<List<E>> lists) => reduce(lists, merge);
+  /// 可空
+  static List<E>? flatten<E>(List<List<E>> lists) => reduce(lists, merge);
 
   /// Merge two Iterable
   /// List<String> a = ['a', 'b', 'c'];
   /// List<String> b = ['1', '2', '3'];
   /// List<String> listMerge = Collections.merge(a, b) // [a, b, c, 1, 2, 3]
-  static List<T> merge<T>(Iterable<T> a, Iterable<T> b) =>
+  static List<T> merge<T>(Iterable<T>? a, Iterable<T>? b) =>
       <T>[]..addAll(a ?? <T>[])..addAll(b ?? <T>[]);
 
-  static List<T> clone<T>(Iterable<T> a) =>
+  static List<T> clone<T>(Iterable<T>? a) =>
       (a == null || a.isEmpty) ? <T>[] : (<T>[]..addAll(a));
 
   /// Cast map to list
@@ -47,11 +50,12 @@ class Collections {
   /// List<String> list = ['1', '2', null, '3', null];
   /// print(list)                       // [1, 2, null, 3, null]
   /// print(Collections.compact(list)); // [1, 2, 3]
-  static List<T> compact<T>(Iterable<T> list, {bool growable = true}) =>
-      list?.where((T e) => e != null)?.toList(growable: growable);
+  /// 可空 list?
+  static List<T>? compact<T>(Iterable<T>? list, {bool growable = true}) =>
+      list?.where((T? e) => e != null)?.toList(growable: growable);
 
   /// Check if an Object is Empty.
-  static bool isEmpty(Object value) {
+  static bool isEmpty(Object? value) {
     if (value == null) {
       return true;
     } else {
diff --git a/lib/src/utils/tuple.dart b/lib/src/utils/tuple.dart
index bf791a4..82d3278 100644
--- a/lib/src/utils/tuple.dart
+++ b/lib/src/utils/tuple.dart
@@ -13,7 +13,7 @@ class Tuple0<T0> {
 /// Represents a 1-tuple
 /// Mutable data types are easier to use.
 class Tuple1<T0> {
-  T0 i0;
+  T0? i0;
 
   Tuple1([this.i0]);
 
@@ -30,10 +30,10 @@ class Tuple1<T0> {
 /// Represents a 2-tuple or pair.
 class Tuple2<T0, T1> {
   /// First item of the tuple
-  T0 i0;
+  T0? i0;
 
   /// Second item of the tuple
-  T1 i1;
+  T1? i1;
 
   /// Create a new tuple value with the specified items.
   Tuple2([this.i0, this.i1]);
@@ -51,9 +51,9 @@ class Tuple2<T0, T1> {
 
 /// Represents a 3-tuple or pair.
 class Tuple3<T0, T1, T2> {
-  T0 i0;
-  T1 i1;
-  T2 i2;
+  T0? i0;
+  T1? i1;
+  T2? i2;
 
   Tuple3([this.i0, this.i1, this.i2]);
 
@@ -70,10 +70,10 @@ class Tuple3<T0, T1, T2> {
 
 /// Represents a 4-tuple or pair.
 class Tuple4<T0, T1, T2, T3> {
-  T0 i0;
-  T1 i1;
-  T2 i2;
-  T3 i3;
+  T0? i0;
+  T1? i1;
+  T2? i2;
+  T3? i3;
 
   Tuple4([this.i0, this.i1, this.i2, this.i3]);
 
@@ -95,11 +95,11 @@ class Tuple4<T0, T1, T2, T3> {
 
 /// Represents a 5-tuple or pair.
 class Tuple5<T0, T1, T2, T3, T4> {
-  T0 i0;
-  T1 i1;
-  T2 i2;
-  T3 i3;
-  T4 i4;
+  T0? i0;
+  T1? i1;
+  T2? i2;
+  T3? i3;
+  T4? i4;
 
   Tuple5([this.i0, this.i1, this.i2, this.i3, this.i4]);
 
@@ -122,12 +122,12 @@ class Tuple5<T0, T1, T2, T3, T4> {
 
 /// Represents a 6-tuple or pair.
 class Tuple6<T0, T1, T2, T3, T4, T5> {
-  T0 i0;
-  T1 i1;
-  T2 i2;
-  T3 i3;
-  T4 i4;
-  T5 i5;
+  T0? i0;
+  T1? i1;
+  T2? i2;
+  T3? i3;
+  T4? i4;
+  T5? i5;
 
   Tuple6([this.i0, this.i1, this.i2, this.i3, this.i4, this.i5]);
 
diff --git a/pubspec.yaml b/pubspec.yaml
index 4ef550d..d3f9d2c 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -5,10 +5,11 @@ author: Alibaba Xianyu Team <tino.wjf@alibaba-inc.com>
 homepage: https://github.com/alibaba/fish-redux
 
 environment:
-    sdk: ">=2.2.0 <3.0.0"
+    sdk: ">=2.12.0 <3.0.0"
 dependencies:
     flutter:
         sdk: flutter
+    collection: ^1.15.0-nullsafety.4
 
 dev_dependencies:
     test: ^1.5.1
diff --git a/test/lib/redux_component/component_test.dart b/test/lib/redux_component/component_test.dart
index d292869..6d9df17 100644
--- a/test/lib/redux_component/component_test.dart
+++ b/test/lib/redux_component/component_test.dart
@@ -147,7 +147,7 @@ void main() {
       expect(componentWidget, isNotNull);
 
       expect(
-          const TypeMatcher<ComponentWrapper>().check(componentWidget), isTrue);
+          const TypeMatcher<ComponentWrapper>(), componentWidget);
     });
 
     testWidgets('build', (WidgetTester tester) async {
diff --git a/test/lib/redux_component/lifecycle_test.dart b/test/lib/redux_component/lifecycle_test.dart
index e120cbd..eccb294 100644
--- a/test/lib/redux_component/lifecycle_test.dart
+++ b/test/lib/redux_component/lifecycle_test.dart
@@ -109,7 +109,7 @@ void main() {
       expect(componentWidget, isNotNull);
 
       expect(
-          const TypeMatcher<ComponentWrapper>().check(componentWidget), isTrue);
+          const TypeMatcher<ComponentWrapper>(), componentWidget);
     });
 
     testWidgets('cycleLife', (WidgetTester tester) async {
diff --git a/test/lib/redux_component/page_test.dart b/test/lib/redux_component/page_test.dart
index 10c2da6..0973d64 100644
--- a/test/lib/redux_component/page_test.dart
+++ b/test/lib/redux_component/page_test.dart
@@ -22,7 +22,7 @@ void main() {
       final Widget pageWidget = page.buildPage(pageInitParams);
       expect(pageWidget, isNotNull);
 
-      expect(const TypeMatcher<PageWrapper>().check(pageWidget), isTrue);
+      expect(const TypeMatcher<PageWrapper>(), pageWidget);
       //expect(pageWidget, TypeMatcher<PageWrapper>());
     });
 
diff --git a/test/pubspec.yaml b/test/pubspec.yaml
index 7337ffd..61a8212 100644
--- a/test/pubspec.yaml
+++ b/test/pubspec.yaml
@@ -5,7 +5,7 @@ author:
 homepage:
 
 environment:
-    sdk: '>=2.0.0-dev.68.0 <3.0.0'
+    sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
     flutter:
diff --git a/test/test_widgets/lib/adapter/adapter.dart b/test/test_widgets/lib/adapter/adapter.dart
index 8652f3c..790fc7c 100644
--- a/test/test_widgets/lib/adapter/adapter.dart
+++ b/test/test_widgets/lib/adapter/adapter.dart
@@ -25,7 +25,7 @@ Widget toDoView(
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -41,7 +41,7 @@ Widget toDoView(
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
@@ -87,7 +87,7 @@ bool toDoListEffect(Action action, Context<ToDoList> ctx) {
     assert(action.payload is Todo);
 
     Todo toDo = ctx.state.list
-        .firstWhere((i) => i.id == action.payload.id, orElse: () => null)
+        .firstWhere((i) => i?.id == action.payload.id, orElse: () => null)!
         .clone();
     toDo.desc = '${toDo.desc}-effect';
     ctx.dispatch(Action(ToDoListAction.edit, payload: toDo));
@@ -123,12 +123,12 @@ ToDoList toDoListReducer(ToDoList state, Action action) {
   } else if (action.type == ToDoListAction.markDone) {
     return state.clone()
       ..list
-          .firstWhere((toDo) => toDo.id == item.id, orElse: () => null)
+          .firstWhere((toDo) => toDo?.id == item.id, orElse: () => null)
           ?.isDone = true;
   } else if (action.type == ToDoListAction.remove) {
-    return state.clone()..list.removeWhere((toDo) => toDo.id == item.id);
+    return state.clone()..list.removeWhere((toDo) => toDo?.id == item.id);
   } else if (action.type == ToDoListAction.edit) {
-    Todo toDo = state.list.firstWhere((toDo) => toDo.id == item.id);
+    Todo toDo = state.list.firstWhere((toDo) => toDo?.id == item.id)!;
     int index = state.list.indexOf(toDo);
     toDo = toDo.clone()..desc = item.desc;
     return state.clone()..list[index] = toDo;
@@ -143,7 +143,7 @@ ListAdapter toDoListAdapter(
   ViewService viewService,
 ) {
   return ListAdapter((context, index) {
-    Todo toDo = state.list[index];
+    Todo toDo = state.list[index]!;
 
     return toDoView(toDo, dispatch, viewService);
   }, state.list.length);
diff --git a/test/test_widgets/lib/adapter/page.dart b/test/test_widgets/lib/adapter/page.dart
index e2578e7..daace1f 100644
--- a/test/test_widgets/lib/adapter/page.dart
+++ b/test/test_widgets/lib/adapter/page.dart
@@ -11,9 +11,9 @@ Widget pageView(
   ViewService viewService,
 ) {
   print('build pageView');
-  ListAdapter listAdapter = viewService.buildAdapter();
+  ListAdapter listAdapter = viewService.buildAdapter()!;
   return ListView.builder(
-      itemBuilder: listAdapter.itemBuilder, itemCount: listAdapter.itemCount);
+      itemBuilder: listAdapter.itemBuilder!, itemCount: listAdapter.itemCount);
 }
 
 const Map pageInitParams = <String, dynamic>{
@@ -45,7 +45,7 @@ const Map pageInitParams = <String, dynamic>{
   ]
 };
 
-ToDoList initState(Map map) => ToDoList.fromMap(map);
+ToDoList initState(Map? map) => ToDoList.fromMap(map!);
 
 class PageWrapper extends StatelessWidget {
   final Widget child;
diff --git a/test/test_widgets/lib/adapter/state.dart b/test/test_widgets/lib/adapter/state.dart
index 5bf7107..a960081 100644
--- a/test/test_widgets/lib/adapter/state.dart
+++ b/test/test_widgets/lib/adapter/state.dart
@@ -1,9 +1,9 @@
 import 'package:fish_redux/fish_redux.dart';
 
 class Todo implements Cloneable<Todo> {
-  String id;
-  String title;
-  String desc;
+  String? id;
+  String? title;
+  String? desc;
   bool isDone = false;
 
   Todo();
@@ -46,7 +46,7 @@ class Todo implements Cloneable<Todo> {
 }
 
 class ToDoList implements Cloneable<ToDoList> {
-  List<Todo> list = <Todo>[];
+  List<Todo?> list = <Todo?>[];
 
   ToDoList();
 
diff --git a/test/test_widgets/lib/component/component.dart b/test/test_widgets/lib/component/component.dart
index 605323d..082a4a4 100644
--- a/test/test_widgets/lib/component/component.dart
+++ b/test/test_widgets/lib/component/component.dart
@@ -21,7 +21,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -38,7 +38,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
diff --git a/test/test_widgets/lib/component/page.dart b/test/test_widgets/lib/component/page.dart
index 6fd8d29..b421398 100644
--- a/test/test_widgets/lib/component/page.dart
+++ b/test/test_widgets/lib/component/page.dart
@@ -31,7 +31,7 @@ Widget toDoListView(
               padding: const EdgeInsets.all(8.0),
               margin: const EdgeInsets.all(8.0),
               color: Colors.grey,
-              child: Text(toDo.desc),
+              child: Text(toDo.desc ?? ''),
               alignment: AlignmentDirectional.center,
             );
           }
@@ -130,7 +130,7 @@ const Map pageInitParams = <String, dynamic>{
   ]
 };
 
-ToDoList initState(Map map) => ToDoList.fromMap(map);
+ToDoList initState(Map? map) => ToDoList.fromMap(map!);
 
 class ToDoComponent0 extends ToDoComponent {}
 
diff --git a/test/test_widgets/lib/component/state.dart b/test/test_widgets/lib/component/state.dart
index 5bf7107..5ac83ab 100644
--- a/test/test_widgets/lib/component/state.dart
+++ b/test/test_widgets/lib/component/state.dart
@@ -1,9 +1,9 @@
 import 'package:fish_redux/fish_redux.dart';
 
 class Todo implements Cloneable<Todo> {
-  String id;
-  String title;
-  String desc;
+  String? id;
+  String? title;
+  String? desc;
   bool isDone = false;
 
   Todo();
diff --git a/test/test_widgets/lib/dynamic_flow_adapter/adapter.dart b/test/test_widgets/lib/dynamic_flow_adapter/adapter.dart
index 2589d64..493210c 100644
--- a/test/test_widgets/lib/dynamic_flow_adapter/adapter.dart
+++ b/test/test_widgets/lib/dynamic_flow_adapter/adapter.dart
@@ -21,7 +21,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -38,7 +38,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
diff --git a/test/test_widgets/lib/dynamic_flow_adapter/component.dart b/test/test_widgets/lib/dynamic_flow_adapter/component.dart
index a6518a7..ce6ca02 100644
--- a/test/test_widgets/lib/dynamic_flow_adapter/component.dart
+++ b/test/test_widgets/lib/dynamic_flow_adapter/component.dart
@@ -21,7 +21,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -38,7 +38,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
diff --git a/test/test_widgets/lib/dynamic_flow_adapter/dynamic_flow_adapter.dart b/test/test_widgets/lib/dynamic_flow_adapter/dynamic_flow_adapter.dart
index 4fbf94a..8908b47 100644
--- a/test/test_widgets/lib/dynamic_flow_adapter/dynamic_flow_adapter.dart
+++ b/test/test_widgets/lib/dynamic_flow_adapter/dynamic_flow_adapter.dart
@@ -39,7 +39,7 @@ final TestDynamicFlowAdapter<ToDoList> testAdapter =
             set: (ToDoList toDoList, List<ItemBean> beans) {
               toDoList.list.clear();
               toDoList.list.addAll(
-                  beans.map<Todo>((ItemBean bean) => bean.data).toList());
+                  beans.map<Todo>((ItemBean bean) => bean.data as dynamic).toList());
             }),
         reducer: toDoListReducer,
         effect: toDoListEffect);
diff --git a/test/test_widgets/lib/dynamic_flow_adapter/page.dart b/test/test_widgets/lib/dynamic_flow_adapter/page.dart
index 463fbc2..5eb444e 100644
--- a/test/test_widgets/lib/dynamic_flow_adapter/page.dart
+++ b/test/test_widgets/lib/dynamic_flow_adapter/page.dart
@@ -12,12 +12,12 @@ Widget pageView(
   ViewService viewService,
 ) {
   print('build pageView');
-  final ListAdapter listAdapter = viewService.buildAdapter();
+  final ListAdapter listAdapter = viewService.buildAdapter()!;
   return Column(
     children: <Widget>[
       Expanded(
           child: ListView.builder(
-              itemBuilder: listAdapter.itemBuilder,
+              itemBuilder: listAdapter.itemBuilder!,
               itemCount: listAdapter.itemCount)),
       Row(
         children: <Widget>[
@@ -84,7 +84,7 @@ bool pageEffect(Action action, Context<ToDoList> ctx) {
   return false;
 }
 
-ToDoList initState(Map map) => ToDoList.fromMap(map);
+ToDoList initState(Map? map) => ToDoList.fromMap(map!);
 
 Widget createDynamicAdapterWidget(BuildContext context) {
   return TestPage<ToDoList, Map>(
diff --git a/test/test_widgets/lib/dynamic_flow_adapter/state.dart b/test/test_widgets/lib/dynamic_flow_adapter/state.dart
index 5bf7107..5ac83ab 100644
--- a/test/test_widgets/lib/dynamic_flow_adapter/state.dart
+++ b/test/test_widgets/lib/dynamic_flow_adapter/state.dart
@@ -1,9 +1,9 @@
 import 'package:fish_redux/fish_redux.dart';
 
 class Todo implements Cloneable<Todo> {
-  String id;
-  String title;
-  String desc;
+  String? id;
+  String? title;
+  String? desc;
   bool isDone = false;
 
   Todo();
diff --git a/test/test_widgets/lib/page/page.dart b/test/test_widgets/lib/page/page.dart
index 4b1fc0f..ad14c81 100644
--- a/test/test_widgets/lib/page/page.dart
+++ b/test/test_widgets/lib/page/page.dart
@@ -23,7 +23,7 @@ Widget toDoView(Todo toDo, BuildContext context, Dispatch dispatch) {
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -39,7 +39,7 @@ Widget toDoView(Todo toDo, BuildContext context, Dispatch dispatch) {
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
@@ -87,7 +87,7 @@ Widget toDoListView(
       Expanded(
           child: ListView.builder(
         itemBuilder: (context, index) {
-          Todo toDo = state.list[index];
+          Todo toDo = state.list[index]!;
           return toDoView(toDo, context, dispatch);
         },
         itemCount: state.list.length,
@@ -142,7 +142,7 @@ bool toDoListEffect(Action action, Context<ToDoList> ctx) {
     assert(action.payload is Todo);
 
     Todo toDo = ctx.state.list
-        .firstWhere((i) => i.id == action.payload.id, orElse: () => null);
+        .firstWhere((Todo? i) => i?.id == action.payload.id, orElse: () => null)!;
 
     assert(toDo != null);
 
@@ -183,14 +183,14 @@ ToDoList toDoListReducer(ToDoList state, Action action) {
   } else if (action.type == ToDoListAction.markDone) {
     return state.clone()
       ..list
-          .firstWhere((toDo) => toDo.id == item.id, orElse: () => null)
+          .firstWhere((toDo) => toDo?.id == item.id, orElse: () => null)
           ?.isDone = true;
   } else if (action.type == ToDoListAction.remove) {
-    return state.clone()..list.removeWhere((toDo) => toDo.id == item.id);
+    return state.clone()..list.removeWhere((toDo) => toDo?.id == item.id);
   } else if (action.type == ToDoListAction.edit) {
     return state.clone()
       ..list
-          .firstWhere((toDo) => toDo.id == item.id, orElse: () => null)
+          .firstWhere((toDo) => toDo?.id == item.id, orElse: () => null)
           ?.desc = item.desc;
   } else {
     return state;
@@ -211,16 +211,16 @@ bool toDoListErrorHandler(Exception exception, Context<ToDoList> ctx) {
 }
 
 Composable<Dispatch> toDoListMiddleware({
-  Dispatch dispatch,
-  Get<ToDoList> getState,
+  required Dispatch dispatch,
+  required Get<ToDoList> getState,
 }) =>
     (Dispatch next) => (Action action) {
           if (action.type == ToDoListAction.middlewareEdit) {
             assert(action.payload is Todo);
 
             Todo toDo = getState().list.firstWhere(
-                (i) => i.id == action.payload.id,
-                orElse: () => null);
+                (i) => i?.id == action.payload.id,
+                orElse: () => null)!;
 
             assert(toDo != null);
 
@@ -262,7 +262,7 @@ const Map pageInitParams = <String, dynamic>{
   ]
 };
 
-ToDoList initState(Map map) => ToDoList.fromMap(map);
+ToDoList initState(Map? map) => ToDoList.fromMap(map!);
 
 class PageWrapper extends StatelessWidget {
   final Widget child;
@@ -283,5 +283,5 @@ Widget createPageWidget(BuildContext context) {
       effect: toDoListEffectAsync,
 //      shouldUpdate: forbidRefreshWhenAddOrRemove,
 //      onError: toDoListErrorHandler,
-      middleware: [toDoListMiddleware]).buildPage(pageInitParams);
+      middleware: [toDoListMiddleware as dynamic]).buildPage(pageInitParams);
 }
diff --git a/test/test_widgets/lib/page/state.dart b/test/test_widgets/lib/page/state.dart
index 5bf7107..a960081 100644
--- a/test/test_widgets/lib/page/state.dart
+++ b/test/test_widgets/lib/page/state.dart
@@ -1,9 +1,9 @@
 import 'package:fish_redux/fish_redux.dart';
 
 class Todo implements Cloneable<Todo> {
-  String id;
-  String title;
-  String desc;
+  String? id;
+  String? title;
+  String? desc;
   bool isDone = false;
 
   Todo();
@@ -46,7 +46,7 @@ class Todo implements Cloneable<Todo> {
 }
 
 class ToDoList implements Cloneable<ToDoList> {
-  List<Todo> list = <Todo>[];
+  List<Todo?> list = <Todo?>[];
 
   ToDoList();
 
diff --git a/test/test_widgets/lib/source_flow_adapter/adapter.dart b/test/test_widgets/lib/source_flow_adapter/adapter.dart
index 2589d64..493210c 100644
--- a/test/test_widgets/lib/source_flow_adapter/adapter.dart
+++ b/test/test_widgets/lib/source_flow_adapter/adapter.dart
@@ -21,7 +21,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -38,7 +38,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
diff --git a/test/test_widgets/lib/source_flow_adapter/component.dart b/test/test_widgets/lib/source_flow_adapter/component.dart
index a6518a7..ce6ca02 100644
--- a/test/test_widgets/lib/source_flow_adapter/component.dart
+++ b/test/test_widgets/lib/source_flow_adapter/component.dart
@@ -21,7 +21,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -38,7 +38,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
diff --git a/test/test_widgets/lib/source_flow_adapter/page.dart b/test/test_widgets/lib/source_flow_adapter/page.dart
index 6152bda..c4d2f0a 100644
--- a/test/test_widgets/lib/source_flow_adapter/page.dart
+++ b/test/test_widgets/lib/source_flow_adapter/page.dart
@@ -12,12 +12,12 @@ Widget pageView(
   ViewService viewService,
 ) {
   print('build pageView');
-  final ListAdapter listAdapter = viewService.buildAdapter();
+  final ListAdapter listAdapter = viewService.buildAdapter()!;
   return Column(
     children: <Widget>[
       Expanded(
           child: ListView.builder(
-              itemBuilder: listAdapter.itemBuilder,
+              itemBuilder: listAdapter.itemBuilder!,
               itemCount: listAdapter.itemCount)),
       Row(
         children: <Widget>[
@@ -84,7 +84,7 @@ bool pageEffect(Action action, Context<ToDoList> ctx) {
   return false;
 }
 
-ToDoList initState(Map map) => ToDoList.fromMap(map);
+ToDoList initState(Map? map) => ToDoList.fromMap(map!);
 
 Widget createDynamicAdapterWidget(BuildContext context) {
   return TestPage<ToDoList, Map>(
diff --git a/test/test_widgets/lib/source_flow_adapter/state.dart b/test/test_widgets/lib/source_flow_adapter/state.dart
index 4a73afe..240d546 100644
--- a/test/test_widgets/lib/source_flow_adapter/state.dart
+++ b/test/test_widgets/lib/source_flow_adapter/state.dart
@@ -1,9 +1,9 @@
 import 'package:fish_redux/fish_redux.dart';
 
 class Todo implements Cloneable<Todo> {
-  String id;
-  String title;
-  String desc;
+  String? id;
+  String? title;
+  String? desc;
   bool isDone = false;
 
   Todo();
@@ -88,7 +88,7 @@ class ToDoList extends ItemListLike implements Cloneable<ToDoList> {
 
   @override
   ItemListLike updateItemData(int index, Object data, bool isStateCopied) {
-    list[index] = data;
+    list[index] = data as dynamic;
     return this;
   }
 }
diff --git a/test/test_widgets/lib/static_flow_adapter/component.dart b/test/test_widgets/lib/static_flow_adapter/component.dart
index 1a34451..0a4c57c 100644
--- a/test/test_widgets/lib/static_flow_adapter/component.dart
+++ b/test/test_widgets/lib/static_flow_adapter/component.dart
@@ -21,7 +21,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   height: 28.0,
                   color: Colors.yellow,
                   child: Text(
-                    toDo.title,
+                    toDo.title ?? '',
                     style: TextStyle(fontSize: 16.0),
                   ),
                   alignment: AlignmentDirectional.centerStart,
@@ -38,7 +38,7 @@ Widget toDoView(Todo toDo, Dispatch dispatch, ViewService viewService) {
                   padding: const EdgeInsets.all(8.0),
                   height: 60.0,
                   color: Colors.grey,
-                  child: Text(toDo.desc, style: TextStyle(fontSize: 14.0)),
+                  child: Text(toDo.desc ?? '', style: TextStyle(fontSize: 14.0)),
                   alignment: AlignmentDirectional.centerStart,
                 ),
                 onTap: () {
diff --git a/test/test_widgets/lib/static_flow_adapter/page.dart b/test/test_widgets/lib/static_flow_adapter/page.dart
index 64d37ad..745842a 100644
--- a/test/test_widgets/lib/static_flow_adapter/page.dart
+++ b/test/test_widgets/lib/static_flow_adapter/page.dart
@@ -11,9 +11,9 @@ Widget pageView(
   ViewService viewService,
 ) {
   print('build pageView');
-  ListAdapter listAdapter = viewService.buildAdapter();
+  ListAdapter listAdapter = viewService.buildAdapter()!;
   return ListView.builder(
-      itemBuilder: listAdapter.itemBuilder, itemCount: listAdapter.itemCount);
+      itemBuilder: listAdapter.itemBuilder!, itemCount: listAdapter.itemCount);
 }
 
 const Map pageInitParams = <String, dynamic>{
@@ -45,7 +45,7 @@ const Map pageInitParams = <String, dynamic>{
   ]
 };
 
-ToDoList initState(Map map) => ToDoList.fromMap(map);
+ToDoList initState(Map? map) => ToDoList.fromMap(map!);
 
 Widget createStaticAdapterWidget(BuildContext context) {
   return TestPage<ToDoList, Map>(
diff --git a/test/test_widgets/lib/static_flow_adapter/state.dart b/test/test_widgets/lib/static_flow_adapter/state.dart
index 5bf7107..a960081 100644
--- a/test/test_widgets/lib/static_flow_adapter/state.dart
+++ b/test/test_widgets/lib/static_flow_adapter/state.dart
@@ -1,9 +1,9 @@
 import 'package:fish_redux/fish_redux.dart';
 
 class Todo implements Cloneable<Todo> {
-  String id;
-  String title;
-  String desc;
+  String? id;
+  String? title;
+  String? desc;
   bool isDone = false;
 
   Todo();
@@ -46,7 +46,7 @@ class Todo implements Cloneable<Todo> {
 }
 
 class ToDoList implements Cloneable<ToDoList> {
-  List<Todo> list = <Todo>[];
+  List<Todo?> list = <Todo?>[];
 
   ToDoList();
 
diff --git a/test/test_widgets/lib/static_flow_adapter/static_flow_adapter.dart b/test/test_widgets/lib/static_flow_adapter/static_flow_adapter.dart
index a9b826d..e0a7a2e 100644
--- a/test/test_widgets/lib/static_flow_adapter/static_flow_adapter.dart
+++ b/test/test_widgets/lib/static_flow_adapter/static_flow_adapter.dart
@@ -34,7 +34,7 @@ ToDoList toDoListReducer(ToDoList state, Action action) {
   if (action.type == ToDoListAction.add) {
     return state.clone()..list.add(action.payload);
   } else if (action.type == ToDoListAction.remove) {
-    Todo toDo = state.list.firstWhere((toDo) => toDo?.id == action.payload.id);
+    Todo? toDo = state.list.firstWhere((Todo? toDo) => toDo?.id == action.payload.id);
     int index = state.list.indexOf(toDo);
     return state.clone()..list[index] = null;
   } else {
@@ -52,19 +52,19 @@ class ToDoComponent3 extends ToDoComponent {}
 
 final testAdapter = TestStaticFlowAdapter<ToDoList>(slots: [
   ConnOp<ToDoList, Todo>(
-          get: (toDoList) => toDoList.list[0],
+          get: (ToDoList toDoList) => toDoList.list[0]!,
           set: (toDoList, toDo) => toDoList.list[0] = toDo) +
       ToDoComponent0(),
   ConnOp<ToDoList, Todo>(
-          get: (toDoList) => toDoList.list[1],
+          get: (toDoList) => toDoList.list[1]!,
           set: (toDoList, toDo) => toDoList.list[1] = toDo) +
       ToDoComponent1(),
   ConnOp<ToDoList, Todo>(
-          get: (toDoList) => toDoList.list[2],
+          get: (toDoList) => toDoList.list[2]!,
           set: (toDoList, toDo) => toDoList.list[2] = toDo) +
       ToDoComponent2(),
   ConnOp<ToDoList, Todo>(
-          get: (toDoList) => toDoList.list[3],
+          get: (toDoList) => toDoList.list[3]!,
           set: (toDoList, toDo) => toDoList.list[3] = toDo) +
       ToDoComponent3()
 ], reducer: toDoListReducer, effect: toDoListEffect);
diff --git a/test/test_widgets/lib/test_base.dart b/test/test_widgets/lib/test_base.dart
index e5dca5f..1233e99 100644
--- a/test/test_widgets/lib/test_base.dart
+++ b/test/test_widgets/lib/test_base.dart
@@ -25,16 +25,16 @@ class _StubState extends State<TestStub> {
 
 class TestPage<T extends Cloneable<T>, P> extends Page<T, P> {
   TestPage({
-    @required InitState<T, P> initState,
-    List<Middleware<T>> middleware,
-    @required ViewBuilder<T> view,
-    Reducer<T> reducer,
-    ReducerFilter<T> filter,
-    Effect<T> effect,
-    Dependencies<T> dependencies,
-    ShouldUpdate<T> shouldUpdate,
-    WidgetWrapper wrapper,
-    Key Function(T) key,
+    required InitState<T, P> initState,
+    List<Middleware<T>>? middleware,
+    required ViewBuilder<T> view,
+    Reducer<T>? reducer,
+    ReducerFilter<T>? filter,
+    Effect<T>? effect,
+    Dependencies<T>? dependencies,
+    ShouldUpdate<T>? shouldUpdate,
+    WidgetWrapper? wrapper,
+    Key Function(T)? key,
   }) : super(
           initState: initState,
           middleware: middleware,
@@ -51,14 +51,14 @@ class TestPage<T extends Cloneable<T>, P> extends Page<T, P> {
 
 class TestComponent<T extends Cloneable<T>> extends Component<T> {
   TestComponent({
-    @required ViewBuilder<T> view,
-    Reducer<T> reducer,
-    ReducerFilter<T> filter,
-    Effect<T> effect,
-    Dependencies<T> dependencies,
-    ShouldUpdate<T> shouldUpdate,
-    WidgetWrapper wrapper,
-    Key Function(T) key,
+    required ViewBuilder<T> view,
+    Reducer<T>? reducer,
+    ReducerFilter<T>? filter,
+    Effect<T>? effect,
+    Dependencies<T>? dependencies,
+    ShouldUpdate<T>? shouldUpdate,
+    WidgetWrapper? wrapper,
+    Key Function(T)? key,
   }) : super(
             view: view,
             reducer: reducer,
@@ -72,11 +72,11 @@ class TestComponent<T extends Cloneable<T>> extends Component<T> {
 
 class TestAdapter<T extends Cloneable<T>> extends Adapter<T> {
   TestAdapter({
-    AdapterBuilder<T> adapter,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    ReducerFilter<T> filter,
-    Dependencies<T> dependencies,
+    required AdapterBuilder<T> adapter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    ReducerFilter<T>? filter,
+    Dependencies<T>? dependencies,
   }) : super(
             adapter: adapter,
             reducer: reducer,
@@ -88,21 +88,21 @@ class TestAdapter<T extends Cloneable<T>> extends Adapter<T> {
 class TestStaticFlowAdapter<T extends Cloneable<T>>
     extends StaticFlowAdapter<T> {
   TestStaticFlowAdapter({
-    @required List<Dependent<T>> slots,
-    Reducer<T> reducer,
-    Effect<T> effect,
-    ReducerFilter<T> filter,
+    required List<Dependent<T>> slots,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
+    ReducerFilter<T>? filter,
   }) : super(slots: slots, reducer: reducer, effect: effect, filter: filter);
 }
 
 class TestDynamicFlowAdapter<T extends Cloneable<T>>
     extends DynamicFlowAdapter<T> {
   TestDynamicFlowAdapter({
-    @required Map<String, AbstractLogic<Object>> pool,
-    @required ConnOp<T, List<ItemBean>> connector,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
+    required Map<String, AbstractLogic<Object>> pool,
+    required ConnOp<T, List<ItemBean>> connector,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
   }) : super(
             pool: pool,
             connector: connector,
@@ -111,13 +111,13 @@ class TestDynamicFlowAdapter<T extends Cloneable<T>>
             filter: filter);
 }
 
-class TestSourceFlowAdapter<T extends AdapterSource>
+class TestSourceFlowAdapter<T extends ItemListLike>
     extends SourceFlowAdapter<T> {
   TestSourceFlowAdapter({
-    @required Map<String, AbstractLogic<Object>> pool,
-    ReducerFilter<T> filter,
-    Reducer<T> reducer,
-    Effect<T> effect,
+    required Map<String, AbstractLogic<Object>> pool,
+    ReducerFilter<T>? filter,
+    Reducer<T>? reducer,
+    Effect<T>? effect,
   }) : super(
           pool: pool,
           reducer: reducer,
diff --git a/test/test_widgets/pubspec.yaml b/test/test_widgets/pubspec.yaml
index cde8798..30129b6 100644
--- a/test/test_widgets/pubspec.yaml
+++ b/test/test_widgets/pubspec.yaml
@@ -2,7 +2,7 @@ name: test_widgets
 description: widgets for redux test...
 
 environment:
-    sdk: '>=2.0.0-dev.28.0 <3.0.0'
+    sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
     flutter: