我有一个Stateful Widget,它从它的父级获取一个bloc:
class Page extends StatefulWidget {
@override
State<StatefulWidget> createState() =>
_PageState();
}
class _PageState extends State<Page> {
final TextEditingController mnemonicController = TextEditingController();
final _scaffoldKey = GlobalKey<ScaffoldState>();
@override
Widget build(BuildContext context) {
final MnemonicLogicBloc mnemonicLogicBloc =
BlocProvider.of<MnemonicLogicBloc>(context);
mnemonicLogicBloc.outCheckMnemonic.listen((isCorrect){
if (!isCorrect) {
SnackBar copySnack = SnackBar(content: Text('Wrong Mnemonic!'));
_scaffoldKey.currentState.showSnackBar(copySnack);
}
});
return Scaffold(
key: _scaffoldKey,
body: Container(
width: double.infinity,
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
child: TextField(
controller: mnemonicController,
),
),
RaisedButton(
onPressed: () {
mnemonicLogicBloc.isMnemonicCorrect(mnemonicController.text);
},
child: Text('Check', style: TextStyle(color: Colors.white)),
)
],
),
));
}
}
我想要做的是,当用户按下按钮时,检查插入的字符串是否正确。我在代码块中调用的方法是:
void isMnemonicCorrect(String typedMnemonic){
if(typedMnemonic == _lastGeneratedMnemonic)
_inCheckMnemonic.add(true);
else
_inCheckMnemonic.add(false);
}
_inCheckMnemonic是我的主题的接收器(我使用rxDart),而outCheckMnemonic是我的流。问题是,即使块的“isCorrect”方法被调用了一次,侦听回调也被调用了两次( SnackBar显示了两次)。这一切为什么要发生?
编辑:我只需使用Navigator.push导航到Page():
Navigator.of(context).push(MaterialPageRoute(
builder: (BuildContext context) {
return Page();
}));
我能够检索块是因为,当我的应用程序启动时,我初始化了块:
return runApp(BlocProvider<ApplicationBloc>(
bloc: ApplicationBloc(),
child: BlocProvider<MnemonicLogicBloc>(
bloc: MnemonicLogicBloc(),
child: BlocProvider<HomePageBloc>(
bloc: HomePageBloc(),
child: App(),
),
)
));
发布于 2019-06-10 08:07:26
当您在Navigator
中添加新的Widget
时,避免在构建器中创建该小部件,而是在外部声明一个变量,并在您的构建器中重用该变量,如下所示:
final page = Page();
Navigator.of(context).push(MaterialPageRoute(
builder: (BuildContext context) => page ), );
通过这种更改,我们可以避免以意外的方式多次重新创建我们的小部件。
https://stackoverflow.com/questions/56519093
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