Simple Bloc Counter App Flutter

main.dart

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:equatable/equatable.dart';

void main() {
  runApp(const MyApp());
}

abstract class CounterEvent extends Equatable {
  @override
  List<Object> get props => [];
}

class CounterIncrementEvent extends CounterEvent {}

class CounterDecrementEvent extends CounterEvent {}

class CounterState extends Equatable {
  final int counter;
  const CounterState({required this.counter}) : super();

  @override
  List<Object> get props => [counter];
}

class CounterBloc extends Bloc<CounterEvent, CounterState> {
  CounterBloc() : super(const CounterState(counter: 0)) {
    on<CounterIncrementEvent>(
        (CounterIncrementEvent event, Emitter<CounterState> emit) =>
            emit(CounterState(counter: state.counter + 1)));
    on<CounterDecrementEvent>(
        (CounterDecrementEvent event, Emitter<CounterState> emit) =>
            emit(CounterState(counter: state.counter - 1)));
  }
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Counter App using Bloc',
        home: BlocProvider<CounterBloc>(
            create: (_) => CounterBloc(), child: const App()));
  }
}

class App extends StatelessWidget {
  const App({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final counter = context.select((CounterBloc bloc) => bloc.state.counter);
    return Scaffold(
        appBar: AppBar(),
        body: Center(
            child:
                Text(counter.toString(), style: const TextStyle(fontSize: 70))),
        floatingActionButton:
            BlocBuilder<CounterBloc, CounterState>(builder: (context, state) {
          return Row(
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: [
                FloatingActionButton(
                    child: const Icon(Icons.add),
                    onPressed: () {
                      context.read<CounterBloc>().add(CounterIncrementEvent());
                    }),
                FloatingActionButton(
                    child: const Icon(Icons.remove),
                    onPressed: () {
                      context.read<CounterBloc>().add(CounterDecrementEvent());
                    })
              ]);
        }));
  }
}