State in StateLess widget

in Flutter

Handling state in a widget needs it extends StatefulWidget But if you want to get notified of state changes in a StatelessWidget, you can use ValueNotifier

ValueNotifier definition

final ValueNotifier<int> _counter = ValueNotifier<int>(0);

and using this ValueNotifier in widget tree

ValueListenableBuilder(
    valueListenable: _counter,
    builder: (context, _, __) {
      return Text(
        '${_counter.value}',
        style: Theme.of(context).textTheme.headline4,
      );
    }),