最近在玩flutter,遇到了snackbar弹不出的情况,log显示这个

显示不出 snackbar 的代码差不多长这样,由于我的代码高亮插件不支持dartlang,就用java代替一下了。。
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> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: RaisedButton(
onPressed: () {
print("Tap");
Scaffold.of(context)
.showSnackBar(new SnackBar(content: Text('Test')));
},
child: new Container(
padding: new EdgeInsets.all(12.0),
child: new Text('Flat Button'),
),
)),
);
}
}
我的解决解决方法是,新建个snackbar类,内容如下。
import 'package:flutter/material.dart';
class snackBar {
static SnackBarByKey(final GlobalKey scaffoldkey,
BuildContext context, String str) {
final snackBar = new SnackBar(content: new Text(str));
scaffoldkey.currentState.showSnackBar(snackBar);
}
}
然后在 main.dart import 这个文件,再修改一下代码,添加一个globalkey,改成这样
import 'package:flutter/material.dart';
import './snackbar.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 {
GlobalKey scaffoldKey = new GlobalKey();
@override
Widget build(BuildContext context) {
return Scaffold(
key: scaffoldKey,
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: RaisedButton(
onPressed: () {
snackBar.SnackBarByKey(scaffoldKey, context, "Test");
// print("Tap");
// Scaffold.of(context)
// .showSnackBar(new SnackBar(content: Text('Test')));
},
child: new Container(
padding: new EdgeInsets.all(12.0),
child: new Text('Flat Button'),
),
)),
);
}
}
这样就可以了,就是增加了第2、28、33、40行的代码而已,效果如下。

为啥这dart的自动格式化是2空格的缩进,异端啊….
我在stackoverflow上走到一个方案,就是搞一个globalKey,是可以正常使用的