Dart 在无状态小部件中使用StatefulBuilder时使用dispose（）

我正在使用一个

StatefulBuilder

小部件来更新我的值，一切正常

StatefulBuilder(
      builder: (BuildContext context, StateSetter setState) {
   return Mywidget();
});

由于此小部件位于选项卡视图中，所以当我滚动到下一个选项卡时，控制台中会出现以下异常

E/flutter ( 7147): [ERROR:flutter/shell/common/shell.cc(188)] Dart Error: Unhandled exception:
E/flutter ( 7147): setState() called after dispose(): _StatefulBuilderState#09a22(lifecycle state: defunct, not mounted)
E/flutter ( 7147): This error happens if you call setState() on a State object for a widget that no longer appears in the widget tree (e.g., whose parent widget no longer includes the widget in its build). This error can occur when code calls setState() from a timer or an animation callback. The preferred solution is to cancel the timer or stop listening to the animation in the dispose() callback. Another solution is to check the "mounted" property of this object before calling setState() to ensure the object is still in the tree.
E/flutter ( 7147): This error might indicate a memory leak if setState() is being called because another object is retaining a reference to this State object after it has been removed from the tree. To avoid memory leaks, consider breaking the reference to this object during dispose().
E/flutter ( 7147): #0      State.setState.<anonymous closure> (package:flutter/src/widgets/framework.dart:1097:9)
E/flutter ( 7147): #1      State.setState (package:flutter/src/widgets/framework.dart:1123:6)
E/flutter ( 7147): #2      ImageItem.actionColumn.<anonymous closure>.<anonymous closure> (package:silkthread/widgets/image_item.dart:197:19)
E/flutter ( 7147): #3      _RootZone.runUnary (dart:async/zone.dart:1379:54)
E/flutter ( 7147): #4      _FutureListener.handleValue (dart:async/future_impl.dart:129:18)
E/flutter ( 7147): #5      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:642:45)
E/flutter ( 7147): #6      Future._propagateToListeners (dart:async/future_impl.dart:671:32)
E/flutter ( 7147): #7      Future._complete (dart:async/future_impl.dart:476:7)
E/flutter ( 7147): #8      _SyncCompleter.complete (dart:async/future_impl.dart:51:12)
E/flutter ( 7147): #9      _RootZone.runUnary (dart:async/zone.dart:1379:54)
E/flutter ( 7147): #10     _FutureListener.handleValue (dart:async/future_impl.dart:129:18)
E/flutter ( 7147): #11     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:642:45)
E/flutter ( 7147): #12     Future._propagateToListeners (dart:async/future_impl.dart:671:32)
E/flutter ( 7147): #13     Future._complete (dart:async/future_impl.dart:476:7)
E/flutter ( 7147): #14     _SyncCompleter.complete (dart:async/future_impl.dart:51:12)
E/flutter ( 7147): #15     _AsyncAwaitCompleter.complete.<anonymous closure> (dart:async/runtime/libasync_patch.dart:33:20)
E/flutter ( 7147): #16     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
E/flutter ( 7147): #17     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)

包装你的代码

if(mounted) {
  setState(() { ... });
}

---

要避免在未安装小部件时调用

setState（）

。

创建并实现自己的StatefulBuilder，请添加dispose方法，如下所示：

import 'package:flutter/material.dart';

typedef Disposer = void Function();

class MyStatefulBuilder extends StatefulWidget {
  const MyStatefulBuilder({
    Key key,
    @required this.builder,
    @required this.dispose,
  }) : assert(builder != null),
        super(key: key);

  final StatefulWidgetBuilder builder;
  final Disposer dispose;

  @override
  _MyStatefulBuilderState createState() => _MyStatefulBuilderState();
}

class _MyStatefulBuilderState extends State<MyStatefulBuilder> {
  @override
  Widget build(BuildContext context) => widget.builder(context, setState);

  @override
  void dispose() {
    super.dispose();
    widget.dispose();
  }
}

return AlertDialog(
        title: Text('Hello, world.'),
        content: MyStatefulBuilder(
          dispose: () {
            print('dispose!!!!!!!!!!!!');
          },
          builder: (BuildContext context, StateSetter setState) {
            return Container();
          }
    )
);

---

当在StatefulBuilder的builder方法中使用时，它会显示未定义的名称。很难说。你能给你的问题添加更多的代码吗？它应该在你的

状态中，扩展的类我认为没有好的方法来解决这个问题。您可以通过<代码> GULALKEY < /代码>，以便能够访问该状态并查询<代码>安装的属性<>代码StuteBuuBuffer-<代码>，但我不认为这是一个好方法。我建议在有状态的小部件中使用
StatefulBuilder
，并创建一个问题，让
StatefulBuilder
检查
挂载
，或者将
state
传递给生成器，以便自定义代码能够检查自身。我建议根本不要使用有状态的builder。这很少是个好主意。更喜欢一个有州的小部件而不是哦，伙计，如果可以的话，我会放弃这5票！谢谢
return AlertDialog(
        title: Text('Hello, world.'),
        content: MyStatefulBuilder(
          dispose: () {
            print('dispose!!!!!!!!!!!!');
          },
          builder: (BuildContext context, StateSetter setState) {
            return Container();
          }
    )
);