How to call a method from one statefulWidget in another Widget (Flutter)

[kcwu229]

In Flutter, you can call a method from one StatefulWidget in another Widget by using a combination of GlobalKey and the State class.

Here's a step-by-step guide on how to achieve this:

1. Define a GlobalKey in the parent StatefulWidget:

   • In the parent StatefulWidget, create a GlobalKey and assign it to the child StatefulWidget.

   • For example, if the parent StatefulWidget is called ParentWidget and the child StatefulWidget is called ChildWidget, you can define the GlobalKey like this:

     class ParentWidgetState extends State<ParentWidget> {
     final _childWidgetKey = GlobalKey<ChildWidgetState>();
     
     // Other code...
     }

2. Pass the GlobalKey to the child StatefulWidget:

   • In the build method of the parent StatefulWidget, pass the GlobalKey to the child StatefulWidget using the key parameter.

     @override
     Widget build(BuildContext context) {
     return ChildWidget(key: _childWidgetKey);
     }

3. Access the State of the child StatefulWidget:

   • In the parent StatefulWidget, you can now access the State of the child StatefulWidget using the GlobalKey.

     void callChildWidgetMethod() {
     _childWidgetKey.currentState?.someMethod();
     }

   • Replace someMethod() with the name of the method you want to call in the child StatefulWidget.

4. Implement the method in the child StatefulWidget:

   • In the child StatefulWidget, define the method you want to call from the parent StatefulWidget.

     class ChildWidgetState extends State<ChildWidget> {
     void someMethod() {
      // Implement the method here
     }
     
     // Other code...
     }

Here's a complete example demonstrating this process:

class ParentWidget extends StatefulWidget {
  @override
  ParentWidgetState createState() => ParentWidgetState();
}

class ParentWidgetState extends State<ParentWidget> {
  final _childWidgetKey = GlobalKey<ChildWidgetState>();

  void callChildWidgetMethod() {
    _childWidgetKey.currentState?.someMethod();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        ChildWidget(key: _childWidgetKey),
        ElevatedButton(
          onPressed: callChildWidgetMethod,
          child: Text('Call Child Widget Method'),
        ),
      ],
    );
  }
}

class ChildWidget extends StatefulWidget {
  ChildWidget({Key? key}) : super(key: key);

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

class ChildWidgetState extends State<ChildWidget> {
  void someMethod() {
    // Implement the method here
    print('Child Widget Method Called');
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('Child Widget'),
    );
  }
}

In this example, the ParentWidget has a GlobalKey that is assigned to the ChildWidget. When the "Call Child Widget Method" button is pressed, the callChildWidgetMethod() function is called, which in turn calls the someMethod() function in the ChildWidgetState.