complete flutter code

main.dart

  Widget build(BuildContext context) {
    final ButtonStyle style = TextButton.styleFrom(
      foregroundColor: Theme.of(context).colorScheme.onPrimary,
    );
    return Scaffold (
      appBar: AppBar(
        leading: Icon(Icons.favorite),
        title: const Text('The Title'),
        actions: <Widget>[
          TextButton(
            style: style,
            onPressed: () {},
            child: const Text('RED'),
          ),
          TextButton(
            style: style,
            onPressed: () {},
            child: const Text('GREEN'),
          ),
          TextButton(
            style: style,
            onPressed: () {},
            child: const Text('BLUE'),
          ),
        ],

      ),
    );
  }