rx_notifier_erxample.dart

class HomePage extends StatelessWidget {

  final counter = RxNotifier<int>(0);
  
  _increment() => counter.value++;
  
  @override
  Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(title: Text('Counter')),
        body: Center(
          child: RxBuilder(
            builder: (_) {
                return Text('${counter.value}');
            }
        ),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.plus_one),
        onPressed: _increment,
      ),
    );
  }
}