如何传递上下文以在颤振中显示警报对话框

Question

我查看了有关如何显示AlertDialog的SO问题，因此在Android Studio生成的启动应用程序中，我尝试了一下，但是传递BuildContext是一个问题，因此另一个SO答案对我有帮助。

但在那之后，对话框仍然没有出现，这里是代码。

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pressed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
//   onPressed: _incrementCounter,
onPressed: () => showAlertDialog,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}

showAlertDialog(BuildContext context) {
// set up the button
Widget okButton = FlatButton(
child: Text("OK"),
onPressed: () { },
);
// set up the AlertDialog
AlertDialog alert = AlertDialog(
title: Text("My title"),
content: Text("This is my message."),
actions: [
okButton,
],
);
// show the dialog
showDialog(
context: context,
builder: (BuildContext context) {
return alert;
},
);
}
}

我尝试调试，但显示警报对话框没有被触发。

Answer 1

问题是你没有将上下文传递给你的showAlertDialog函数，而是尝试将其称为showAlertDialog(context(。