I have a class extends StatelessWidget. When try call SnackBars in Scaffold like:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
actions: <Widget>[
IconButton(
splashRadius: 18,
icon: const Icon(Icons.thumb_up),
tooltip: 'Like the app',
onPressed: () {
final SnackBar snackBar = SnackBar(
duration: const Duration(seconds: 1),
content: const Text('Registered as you like the application.'),
action: SnackBarAction(
label: 'Undo',
onPressed: () {},
),
);
ScaffoldMessenger.of(context).showSnackBar(snackBar);
},
),
],
title: const Text('My Application'),),
body: const Center(
child: Text("Hello World!"),)
);
}
}
when run the application show error like:
Exception has occurred. FlutterError (No ScaffoldMessenger widget found. MyApp widgets require a ScaffoldMessenger widget ancestor. The specific widget that could not find a ScaffoldMessenger ancestor was: MyApp The ancestors of this widget were: [root] Typically, the ScaffoldMessenger widget is introduced by the MaterialApp at the top of your application widget tree.)
I found the solution for the problem but first: why the error happened? It Fails because ScaffoldMessenger.of(context) doesn't find anything above this widget's context. the solution to use Builder class as follows:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
actions: <Widget>[
Builder(
builder: (BuildContext context) {
return IconButton(
splashRadius: 18,
icon: const Icon(Icons.thumb_up),
tooltip: 'Like the app',
onPressed: () {
final SnackBar snackBar = SnackBar(
duration: const Duration(seconds: 1),
content: const Text(
'Registered as you like the application.'),
action: SnackBarAction(
label: 'Undo',
onPressed: () {},
),
);
ScaffoldMessenger.of(context).showSnackBar(snackBar);
},
);
},
),
],
title: const Text('My Application'),
),
body: const Center(
child: Text("Hello World!"),
)),
);
}
}