setState 以非常具体的方式重建。你可以在这里阅读：
https://api.flutter.dev/flutter/widgets/State/setState.html
在简单的世界中 setState 调用最近的构建（我认为这并不完全正确，但这种直觉对我有用）
在您的代码中，当您点击右小部件并调用 setState 时，只会重建右小部件。
所以这是简单的解决方案：
使左右小部件无状态。
在行中的主屏幕中添加gestureDetector（或我的示例中的textButton）并在此处调用setState。当你这样做时，所有 homeSreen 都将被重建，所以左右小部件也是如此。你的清单将是实际的。这是一个例子：
List<String> ListOfZzZ = [];
class homescreen extends StatefulWidget {
@override
_homescreenState createState() => _homescreenState();
}
class _homescreenState extends State<homescreen> {
@override
Widget build(BuildContext context) {
return Material(
child: Scaffold(
body: Row(
children: [
Expanded(
child: TextButton(
onPressed: () => setState(() {
ListOfZzZ.add("ZzZ");
}),
child: RightSidewidget())),
Expanded(child: LeftSideWidget())
],
)),
);
}
}
class RightSidewidget extends StatelessWidget {
const RightSidewidget({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
color: Colors.amber[50],
child: Text("add new ZzZ"),
);
}
}
class LeftSideWidget extends StatelessWidget {
const LeftSideWidget({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Container(
child: ListView.builder(
itemCount: ListOfZzZ.length,
itemBuilder: (context, index) => Text(ListOfZzZ[index])),
);
}
}
使用一些像 bloc 这样的状态管理器是困难的，但更优雅和更好的方法。这里是官方网站：https://bloclibrary.dev/#/gettingstarted
有很多教程和解释。但这不是 5 分钟的解决方案。
编辑：我用 BLoC 做了一些解决方案。我希望这会有所帮助。我在 7.0.1 版本中使用了 flutter_bloc 和 equatable 包
void main() {
EquatableConfig.stringify = kDebugMode;
Bloc.observer = SimpleBlocObserver();
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Scaffold(
appBar: AppBar(
title: Text('myList'),
),
body: BlocProvider(
create: (context) => MylistBloc()..add(AddToList('Start')),
child: Row(
children: [
Expanded(flex: 1, child: buttonsPanel()),
Expanded(flex: 1, child: ListOfZzZ()),
],
),
),
),
);
}
}
class ListOfZzZ extends StatefulWidget {
const ListOfZzZ({Key? key}) : super(key: key);
@override
_ListOfZzZState createState() => _ListOfZzZState();
}
class _ListOfZzZState extends State<ListOfZzZ> {
late MylistBloc _mylistBloc;
@override
Widget build(BuildContext context) {
return BlocBuilder<MylistBloc, MylistState>(
//builder: (context, state) {return ListView.builder(itemBuilder: (BuildContext context,int index){return ListTile(title: state.positions[index];)},);},
builder: (context, state) {
if (state.positions.isEmpty) {
return const Center(child: Text('no posts'));
} else {
return ListView.builder(
itemBuilder: (BuildContext context, int index) {
return ListTile(title: Text(state.positions[index]));
},
itemCount: state.positions.length,
);
}
},
);
}
}
class buttonsPanel extends StatefulWidget {
const buttonsPanel({Key? key}) : super(key: key);
@override
_buttonsPanelState createState() => _buttonsPanelState();
}
class _buttonsPanelState extends State<buttonsPanel> {
late MylistBloc _mylistBloc;
@override
void initState() {
super.initState();
_mylistBloc = context.read<MylistBloc>();
}
@override
Widget build(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
TextButton(
onPressed: () => {_mylistBloc.add(AddToList('Spam'))},
child: Text('Spam')),
TextButton(
onPressed: () => {_mylistBloc.add(AddToList('Ham'))},
child: Text('Ham')),
],
);
}
class SimpleBlocObserver extends BlocObserver {
@override
void onTransition(Bloc bloc, Transition transition) {
super.onTransition(bloc, transition);
print(transition);
}
@override
void onError(BlocBase bloc, Object error, StackTrace stackTrace) {
print(error);
super.onError(bloc, error, stackTrace);
}
}
class MylistState extends Equatable {
final List<String> positions;
final int lenght;
const MylistState({this.positions = const <String>[], this.lenght = 0});
@override
List<Object> get props => [positions];
@override
String toString() => 'Lenght: {$lenght} Positions: {$positions}';
@override
MylistState copyWith(List<String>? positions) {
return MylistState(positions: positions ?? this.positions);
}
}
abstract class MylistEvent extends Equatable {
const MylistEvent();
@override
List<Object> get props => [];
}
class AddToList extends MylistEvent {
final String posToAdd;
@override
AddToList(this.posToAdd);
}
class MylistBloc extends Bloc<MylistEvent, MylistState> {
MylistBloc() : super(MylistState(positions: const <String>[]));
@override
Stream<MylistState> mapEventToState(
MylistEvent event,
) async* {
if (event is AddToList) {
yield await _mapListToState(state, event.posToAdd);
}
}
Future<MylistState> _mapListToState(
MylistState state, String posToAdd) async {
List<String> positions = [];
positions.addAll(state.positions);
positions.add(posToAdd);
return MylistState(positions: positions, lenght: positions.length);
}
}
}