Stateful Widgets

Widgets with mutable state and setState

A StatefulWidget can change over time. It holds mutable state and rebuilds its UI when that state updates.

Counter

StatefulWidget

Immutable config

_CounterState

int _count = 0

Mutable state

Dart

class Counter extends StatefulWidget {
  const Counter({super.key});

  @override
  State<Counter> createState() =>
    _CounterState();
}

class _CounterState extends State<Counter> {
  int _count = 0; // mutable state

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

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