是否可以从另一个类重建或刷新一个类？
例如，我有一个名为“HomeScreen”的类和一个名为“SubScreen”的类。我可以通过底部导航栏在这和类之间导航。
现在我在 SubScreen 类中进行了一些更改。但是当我通过底部导航栏导航回“HomeScreen”时，旧值仍在“HomeScreen”内。当我关闭并重新打开我的应用程序时，“HomeScreen”中的所有内容都会更新。如何在不关闭应用程序的情况下实现“更新”？
请帮我解决这个问题，我卡在那里差不多好几个星期了...
【问题讨论】：
标签： flutter class widget rebuild
当您导航回该页面时，使用导航器上的 then 刷新主屏幕。我希望它能帮助你实现你的要求
而且我还需要知道您在应用程序中使用 Provider。这意味着它更容易。
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SubScreen()),
).then((_){
setState((){});
});
【讨论】：
仅使用 Statefull 小部件：
子屏幕
class SubScreen extends StatefulWidget {
final Function updateCallback;
SubScreen({@required this.updateCallback});
// rest of your State class
// in the State class, when you want to refresh the HomeScreen, call:
widget.updateCallback(); // or a more safe option: widget.updateCallback?.call();
}
class _HomeScreenState ...{
//where you push the second screen
...
Navigator.push(context, SubScreen(updateCallback: (){
setState((){});
})
...
}
更有效的方法：
您可以阅读有关 state management approaches here 的更多信息
rxDart 示例：
为简单起见，我在主屏幕中创建主题并将主题传递给子屏幕。
子屏幕
class SubScreen extends StatefulWidget {
final BehaviourSubject<SomeModel> stateSubject;
SubScreen({@required this.stateSubject});
// rest of your State class
// in the State class, when you want to refresh the HomeScreen, call:
widget.stateSubject.add(newItems); //newItems is the state that you want to present on the HomeScreen too.
// where you want to use this SomeModel state, wrap your Widget with StreamBuilder<SomeModel>, pass the widget.stateSubject as the stream, and in the builder function you can listen to changes. Example in the build just below
Widget build(BuildContext context){
StreamBuilder<SomeModel>(
stream: widget.stateSubject,
initialData: null, //null be default, but you can set like empty array, or anything you want
builder: (context, snapshot) {
var state = snapshot.data;
// here the state contains the latest value of the subject because its a BehaviourSubject, and you will get every new state that is added to this subject.
return Container;
});
}
}
主屏幕
class _HomeScreenState ...{
final BehaviourSubject<SomeModel> stateSubject = BehaviourSubject.seeded(null); //null by default, but you can set an initial value if you need
//where you push the second screen
...
Navigator.push(context, SubScreen(stateSubject: stateSubject));
...
Widget build(context){
//here you need to wrap your widget where you want to update based on the subject
}
}
【讨论】：