从父类颤振调用子类函数 [英] Flutter calling child class function from parent class

问题描述

代码：

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          leading: IconButton(
            icon: Icon(Icons.help),
            onPressed: () {
              // how can I call methodA from here?
            },
          ),
        ),
        body: HomePage(),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Container();
  }

  void methodA() {}
}

问题：
我想从 onPressed（） methodA（） IconButton 中的$ c>。我该怎么做，我知道如何从子类中调用父级的方法，但是这种用例是不同的。

Question: I want to call methodA() from onPressed() of IconButton. How can I do that, I know how to call parent's method from child class but this use case is different.

推荐答案

感谢GünterZöchbauer将我指向正确的方向。我正在使用 GlobalKey 来完成任务。但是，将 GlobalKey 与护理

Thanks to Günter Zöchbauer for pointing me in right direction. I am using GlobalKey to get the things done. However use GlobalKey with care

GlobalKey<_HomePageState> globalKey = GlobalKey();

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          leading: IconButton(
            icon: Icon(Icons.help),
            onPressed: () {
             globalKey.currentState.methodA();
            },
          ),
        ),
        body: HomePage(key: globalKey),
      ),
    );
  }
}
class HomePage extends StatefulWidget {
  HomePage({Key key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Container();
  }

  void methodA() {}
}

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