Mis vahe on Stateful ja Stateless vidjetidel?

• StatelessWidget:

  • Does not have internal state that can change over time.
  • Widget parameters are set at creation and remain unchanged throughout its lifecycle.
  • Used for displaying static data.
  • Rebuild occurs only when the parent widget rebuilds.
  • Implemented via the build() method.

• StatefulWidget:

  • Has internal state (State) that can change in response to events (user actions, network requests, etc.).
  • Rebuild occurs when setState() is called.
  • Used for creating interactive elements and displaying dynamic data.
  • Consists of two parts: the StatefulWidget itself and the associated State object.

Attribute	StatelessWidget	StatefulWidget
State	None	Has mutable state (State)
Rebuild	When parent rebuilds	When setState() is called
Usage	Static data, non-interactive elements	Interactive elements, dynamic data
Implementation	Only the build() method	createState() and lifecycle methods in State

// Example StatelessWidget
class MyStatelessWidget extends StatelessWidget {
  final String text;

  MyStatelessWidget({required this.text});

  @override
  Widget build(BuildContext context) {
    return Text(text); // Simply displays the passed text
  }
}

// Example StatefulWidget
class MyStatefulWidget extends StatefulWidget {
  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}

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

  void _incrementCounter() {
    setState(() {
      // Change state and trigger rebuild
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Text('Counter:'),
        Text('$_counter'),
        ElevatedButton(
          onPressed: _incrementCounter, // Method on press
          child: Text('Increment'),
        ),
      ],
    );
  }
}