显示对话框SimpleDialog

class SimpleDialogDemo extends StatefulWidget {
  @override
  _SimpleDialogDemoState createState() => _SimpleDialogDemoState();
}

class _SimpleDialogDemoState extends State<SimpleDialogDemo> {
  String _choice = '';

  // 弹出对话框
  Future _openSimpleDialog() async {
    final option = await showDialog(
      context: context,
      builder: (BuildContext context) {
        return SimpleDialog(
          title: Text('你想做什么呢？'),
          children: <Widget>[
            SimpleDialogOption(
              child: Text('吃饭'),
              onPressed: () { Navigator.pop(context, '吃饭');},
            ),
            SimpleDialogOption(
              child: Text('睡觉'),
              onPressed: () { Navigator.pop(context, '睡觉');},
            ),
            SimpleDialogOption(
              child: Text('打豆豆'),
              onPressed: () { Navigator.pop(context, '打豆豆');},
            ),
          ],
        );
      }
    );

    if (option != null) {
      setState(() {
        _choice = option;
      });
    }
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('SimpleDialog'), elevation: 0.0,),
      body: Container(
        padding: EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment:  MainAxisAlignment.center,
          children: <Widget>[
            Text('我想。。。$_choice'),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(onPressed: _openSimpleDialog, child: Icon(Icons.format_list_numbered),),
    );
  }
}

提示对话框AlertDialog

class AlertDialogDemo extends StatefulWidget {
  @override
  _AlertDialogDemoState createState() => _AlertDialogDemoState();
}

class _AlertDialogDemoState extends State<AlertDialogDemo> {
  String _choice = '';
  // 弹出提示对话框
  Future _openAlertDialog() async {
    final action = await showDialog(
      context: context,
      barrierDismissible: false, // 如果要求用户必须点击对话框中的按钮才能让对话框消失，那么就设置这个属性为false
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text('提示'),
          content: Text('你要吃冰淇淋吗？'),
          actions: <Widget>[
            FlatButton(onPressed: () { Navigator.pop(context, 'cancle'); }, child: Text('取消')),
            FlatButton(onPressed: () { Navigator.pop(context, 'sure'); }, child: Text('确定')),
          ],
        );
      }
    );

    setState(() {
      if (action == 'cancle') {
        _choice = '不吃冰淇淋';
      } else if (action == 'sure') {
        _choice = '吃冰淇淋';
      }
    });
  }
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('AlertDialog'), elevation: 0.0,),
      body: Container(
        padding: EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment:  MainAxisAlignment.center,
          children: <Widget>[
            Text('我的选择是$_choice'),
            SizedBox(height: 20,),
            Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                RaisedButton(child: Text('打开提示对话框'), onPressed: _openAlertDialog),
              ],
            ),
          ],
        ),
      ),
    );
  }
}