这是因为要传递给该showDialog方法的上下文是一个context尚未MaterialLocalizations在小部件树中包含小部件的，该MaterialLocalizations小部件被该小部件隐式添加MaterialApp。
要解决此问题，请尝试以下操作：
import 'package:Flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "Test",
home: TestPage(),
);
}
}
class TestPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Test")),
body: Container(
child: Center(
child: RaisedButton(
color: Colors.redAccent,
textColor: Colors.white,
onPressed: () {
testAlert(context);
},
child: Text("PressMe"),
),
),
),
);
}
void testAlert(BuildContext context) {
var alert = AlertDialog(
title: Text("Test"),
content: Text("Done..!"),
);
showDialog(
context: context,
builder: (BuildContext context) {
return alert;
});
}
}
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