Flutter：从另一个类调用SetState（）

很简单，您需要将SinglePlayMode :: toggleCoin函数作为回调发送到dropDownMenu类。

class dropDownMenu extends StatefulWidget {          final _callback; // callback reference holder  //you will pass the callback here in constructor    dropDownMenu( {@required void toggleCoinCallback() } ) :       _callback = toggleCoinCallback;        @override      _dropDownMenuState createState() => _dropDownMenuState();    }    class _dropDownMenuState extends State<dropDownMenu> {      @override      Widget build(BuildContext context) {        return Stack(          children: <Widget> [ Column(   mainAxisAlignment: MainAxisAlignment.end,   children: <Widget>[     Container(       child: Opacity(         opacity: 0.0,         child: FloatingActionButton(heroTag: null,onPressed:  (){  widget?._callback(); // callback calling},         ),       ),   );}      }

然后，当您在SinglePlayerMode类中创建dropDownMenu类实例时，您将执行

    dropDownMenu(       toggleCoinCallback: toogleCoin,    );