BloC Workshop

counter_cubit.dart

import 'package:bloc/bloc.dart';
// Business LOgic Component

class CounterCubit extends Cubit<int> {
  CounterCubit(int? initialValue) : super(initialValue ?? 0);

  void increment() {
    emit(state + 1);
  }

  void decrement() {
    emit(state - 1);
  }

  Future<void> delayedIncrement() async {
    await Future.delayed(const Duration(seconds: 1));
    emit(state + 1);
  }

  Future<void> delayedDecrement() async {
    await Future.delayed(const Duration(seconds: 1));
    emit(state - 1);
  }

  void reset() {
    emit(0);
  }
}

void testCubit() {
  final cubit = CounterCubit(5);
  cubit.state;
  cubit.stream.listen((event) {});
  cubit.increment();
  cubit.delayedIncrement();
  cubit.decrement();
  cubit.close();
}

main.dart

import 'package:bloc_workshop/counter_cubit.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => CounterCubit(0),
      child: MaterialApp(
        home: Scaffold(
          appBar: AppBar(
            title: const Text('Stream Example'),
          ),
          body: Column(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            crossAxisAlignment: CrossAxisAlignment.center,
            mainAxisSize: MainAxisSize.max,
            children: const [
              Counter(),
              ResetCounter(),
            ],
          ),
        ),
      ),
    );
  }
}

class Counter extends StatelessWidget {
  const Counter({super.key});

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        IconButton(
          icon: const Icon(Icons.remove),
          onPressed: () {
            context.read<CounterCubit>().decrement();
          },
        ),
        BlocBuilder<CounterCubit, int>(
          builder: (context, state) {
            return Text('$state');
          },
        ),
        IconButton(
          icon: const Icon(Icons.add),
          onPressed: () {
            context.read<CounterCubit>().increment();
          },
        ),
      ],
    );
  }
}

class ResetCounter extends StatelessWidget {
  const ResetCounter({super.key});

  @override
  Widget build(BuildContext context) {
    return IconButton(
      icon: const Icon(Icons.refresh),
      onPressed: () {
        context.read<CounterCubit>().reset();
      },
    );
  }
}

stream_ex1.dart

Stream<int> generateStream() async* {
  int counter = 1;
  while (true) {
    await Future.delayed(const Duration(seconds: 1));
    yield counter++;
  }
}

main() {
  final stream = generateStream();
  stream.listen((event) {
    print(event);
  });
}

streams.dart

main() async {
  final list = [1, 2, 3];
  list.add(4);
  list.removeAt(list.length - 1);
  for (final item in list) {
    print(item);
  }
  final doubledList = list.map((item) => item * 2).toList();

  final stream = Stream<int>.fromIterable([1, 2, 3]);
  await for (final item in stream) {
    print(item);
  }
  final doubledStream = stream.map((item) => item * 2);
  stream.listen((event) {
    print(event);
  });
}