What is the lifecycle of a Stateful widget in Flutter?

1. createState(): Creates a State object for the widget.
2. initState(): Initializes the state, subscribes to streams, animations. Called once when the widget is created.
3. didChangeDependencies(): Called after initState() and when dependencies change (e.g., InheritedWidget).
4. build(): Builds the user interface. Called during initialization and when the state changes (setState()).
5. didUpdateWidget(): Called when the widget's configuration is updated by the parent widget.
6. setState(): Notifies the framework of internal state changes, leading to a rebuild (build).
7. deactivate(): Called when the State is removed from the widget tree (can happen temporarily, e.g., when switching tabs).
8. dispose(): Cleans up resources: unsubscribes from streams, disposes animation controllers. Called before the State is permanently removed from memory.

// Example of using setState to show state change
class MyStatefulWidget extends StatefulWidget {
  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _counter = 0;

  @override
  void initState() {
    super.initState();
    // Initialization
    // print('initState');
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    // Dependencies changed
    // print('didChangeDependencies');
  }

  @override
  void didUpdateWidget(MyStatefulWidget oldWidget) {
    super.didUpdateWidget(oldWidget);
    // Widget updated
    // print('didUpdateWidget');
  }

  void _incrementCounter() {
    setState(() {
      // Change state, triggers rebuild
      _counter++;
      // print('setState: counter = $_counter');
    });
  }

  @override
  Widget build(BuildContext context) {
    // Build UI
    // print('build');
    return Scaffold(
      appBar: AppBar(
        title: Text('Counter Example'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }

  @override
  void deactivate() {
    super.deactivate();
    // Widget deactivated
    // print('deactivate');
  }

  @override
  void dispose() {
    // Resource cleanup
    // print('dispose');
    super.dispose();
  }
}