Bloc詳細

Bloc詳細

Blocは、Flutterの状態管理パターンです。イベントと状態の分離により、予測可能な状態管理を実現します。

Blocの設定

依存関係の追加

pubspec.yaml

dependencies:
  flutter_bloc: ^8.1.0

Blocの実装

counter_event.dart

abstract class CounterEvent {}
class CounterIncremented extends CounterEvent {}
class CounterDecremented extends CounterEvent {}

// counter_state.dart
class CounterState {
  final int value;
  CounterState(this.value);
}

// counter_bloc.dart
class CounterBloc extends Bloc<CounterEvent, CounterState> {
  CounterBloc() : super(CounterState(0)) {
    on<CounterIncremented>((event, emit) => emit(CounterState(state.value + 1)));
    on<CounterDecremented>((event, emit) => emit(CounterState(state.value - 1)));
  }
}