Flutter

Widgets

Everything in Flutter is a widget. Widgets are either:

• Stateless — immutable, rebuilt from parent input.
• Stateful — hold mutable state via a State object.

class Greeting extends StatelessWidget {
  const Greeting({super.key, required this.name});

  final String name;

  @override
  Widget build(BuildContext context) {
    return Text('Hello, $name!');
  }
}

Layout

• Row / Column — arrange children horizontally/vertically.
• Expanded / Flexible — control how children share space.
• Stack — overlay widgets on top of each other.

State Management

• setState — local widget state.
• Provider / Riverpod — shared app state.

References

• Flutter Documentation
• Flutter Widget Catalog