我试图在Flutter中制作一个带有一些图标的简单AppBar小部件,但我不断收到这个断言:
The following assertion was thrown building IconButton(Icon(IconData(U+0E5D2)); disabled; tooltip:
我几乎只是模仿文档,但这是我的代码:
import 'package:flutter/material.dart';
void main() {
runApp(new MaterialApp(
title: "Stateless Widget Example",
home: new AppBar(title: new Text("App Bar"))
));
}
class AppBar extends StatelessWidget {
AppBar({this.title});
final Widget title;
@override
Widget build(BuildContext context) {
return new Container(
height: 56.0,
padding: const EdgeInsets.symmetric(horizontal: 8.0),
decoration: new BoxDecoration(
color: Colors.cyan,
border: new Border(
bottom: new BorderSide(
width: 1.0,
color: Colors.black
)
)
),
child: new Row (
children: <Widget> [
new IconButton(
icon: new Icon(Icons.menu),
tooltip: 'Navigation menu',
onPressed: null, // null disables the button
),
new Expanded(child: title)
]
)
);
}
}
我觉得我缺少进口商品或其他东西。但是我不确定。也许我的计算机刚刚运转起来,因为Flutter的运行对我来说是个难题。我是Dart和Flutter的新手,所以也许我只是没有看到明显的错误。
最佳答案
IconButton是一个Material Widget,因此您需要在Material父级中使用它,例如,如下所示:
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(title: new Text(widget.title), actions: <Widget>[
new IconButton(
icon: new Icon(Icons.favorite),
tooltip: 'Favorite',
onPressed: () {},
),
new IconButton(
icon: new Icon(Icons.more_vert),
tooltip: 'Navigation menu',
onPressed: () {},
),
]),
body: new Center(
child: new Text('This is the body of the page.'),
),
);
}
关于dart - IconButton引发异常,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/44031376/