Question

我调用有状态窗口小部件页面，并从服务器获取一些信息。如果未找到任何信息，则会警告用户没有任何信息。从抽屉后退按钮，我返回上一页。如果我快速重复往复，则会在IntelliJ IDE中收到控制台消息错误，

E/flutter (22681): [ERROR:flutter/shell/common/shell.cc(181)] Dart Error: Unhandled exception:
E/flutter (22681): setState() called after dispose(): _BillsPayWaterState#66be5(lifecycle state: defunct, not mounted)
E/flutter (22681): 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 (22681): 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 (22681): #0      State.setState.<anonymous closure>

在我的全状态小部件中，我有@override void initState()，我也有@override void dispose()

我的问题是，当我使用抽屉后退按钮时，如何完全处置我的状态控件？

这是小部件的调用

onTap: () {
Navigator.push(
  context,
  SlideRightRoute(widget: new BillsWaterPay(“S02")),
);
}

这是BillsWaterPay小部件

List<List<dynamic>> _userAskBills;

// TODO: KURUM KODU - SABIT TELEFON
String _kurumKodu = "";
String _noDataText = "";

class BillsWaterPay extends StatefulWidget {
  final String title;

  BillsWaterPay(this.title);

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

class _BillsWaterPayState extends State<BillsWaterPay> {

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    _kurumKodu = widget.title;
    _userAskBills;
    _noDataText;
    _loadEverything();
}

Future _loadEverything() async {
    await _getDataFromServer();
}

Future _getDataFromServer() async() {
    …
    …
    if no data
        setState
            _noDataText = “No Data”;  // In here I get an error setState called after dispose

}


@override
void dispose() {
  super.dispose();
      _kurumKodu = widget.title;
    _userAskBills;
    _noDataText;
}

Answer 1

我认为问题是由处理小部件后服务器收到的响应引起的。

在调用setState之前，请检查是否已安装了窗口小部件。这样可以避免您看到的错误：

if no data
  if(mounted) {
    setState
        _noDataText = “No Data”;
  }

Answer 2

由于异步处理小部件后调用setState()时，会显示上述异常。

使用flutter => mounted

的属性来处理此问题

mounted讲述了小部件的可用性。

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

如何完全处置我的有状态小组件？

2 个答案: