AsyncNotifierの使い方

MessageNotifier.dart

const sentenceList = {
  'Your code transforms ideas into reality.',
  'Each bug you fix makes you a stronger developer.',
  'Your dedication to learning is inspiring.',
  'You turn complex problems into elegant solutions.',
  'Your creativity in app design is remarkable.',
  'Every line of code you write is a step towards mastery.',
  'You have a unique talent for making the complex understandable.',
  'Your commitment to quality is evident in your work.',
  'You\'re not just coding; you\'re crafting future technologies.',
  'Your passion for development lights up the path for others.',
};

class MessageNotifier extends AsyncNotifier<String> {
  @override
  String build() => '';

  Future<void> refresh() async {
    final _ = await future;

    state = const AsyncValue.loading();
    await Future.delayed(const Duration(seconds: 1));

    final index = Random().nextInt(sentenceList.length);

    state = AsyncValue.data(sentenceList.elementAt(index));
  }
}

final _messageProvider = AsyncNotifierProvider<MessageNotifier, String>(() {
  return MessageNotifier();
});

widget.dart

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final message = ref.watch(_messageProvider);

    ...
            message.when(
              data: (String text) {
                return Text(text);
              },
              error: (Object error, StackTrace stackTrace) {
                return Container();
              },
              loading: () {
                return const CircularProgressIndicator();
              },
            ),