延迟后如何更改材质按钮的状态？

问题描述

我有一个表情符号列表，我有 [?,?,??,?]，我还有一个没有与之关联的图标的按钮。请参阅此材质按钮。

                     MaterialButton(
                        onpressed: () {},child: Text("",textScaleFactor: 2),shape: CircleBorder(),padding: EdgeInsets.all(16),),

现在，我需要在此按钮内显示上方列表，延迟 1 秒后[?,?]。

解决方法

您也可以使用 Future。

MaterialButton(
 onPressed: () async {
     await Future<void>.delayed(Duration(seconds: 1));
     // your function
     },child: Text('',textScaleFactor: 2),shape: CircleBorder(),padding: EdgeInsets.all(16),),

,

您可以使用 Timer.periodic 来实现这一点。请参阅此示例代码

Link to docs

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> {
  Timer emojiTimer;

  @override
  void initState() {
    emojiTimer = Timer.periodic(const Duration(seconds: 1),(timer) {
      changeEmoji();
    });
    super.initState();
  }

  int randomInt = 0;
  Future<void> changeEmoji() async {
    setState(() {
      var ran = Random();
      randomInt = ran.nextInt(emojiList.length);
    });
  }

  var emojiList = [
    "?","?"," ??","??","?"
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),body: Center(
        child: Text('hello there'),floatingActionButton: FloatingActionButton(
        onPressed: () {
          emojiTimer.cancel();
        },child: Text(emojiList[randomInt]),);
  }
}