Can internal widget state be accessed using its key?

In Flutter, keys (Key) are used to identify widgets in the widget tree and help the framework correctly match and update widgets during UI rebuilds. However, keys are not intended for accessing the internal state of a widget.

To access the state of a StatefulWidget, a GlobalKey is used. With a GlobalKey, you can access the state object and call its methods or retrieve data.

Example:

final GlobalKey<MyWidgetState> myKey = GlobalKey<MyWidgetState>();

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

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

class MyWidgetState extends State<MyWidget> {
  int counter = 0;

  void increment() {
    setState(() {
      counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Text('Counter: $counter');
  }
}

// Usage:
myKey.currentState?.increment();

Thus, a regular Key does not give access to the state, but a GlobalKey does. However, overusing this can complicate the architecture of the application.