Untitled

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

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: BlocProvider(
        create: (_) => TestBloc(),
        child: const MyWidget(),
      ),
    );
  }
}

class MyWidget extends StatefulWidget {
  const MyWidget({Key? key}) : super(key: key);

  @override
  State<MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  @override
  void initState() {
    // context.read<TestBloc>().functionA();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: BlocListener<TestBloc, int>(
        listenWhen: ((previous, current) => current < previous),
        listener: (ctx, state) {
          final snackBar = SnackBar(content: Text('$state'));
          ScaffoldMessenger.of(context).showSnackBar(snackBar);
        },
        child: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Container(
                alignment: Alignment.center,
                child: GestureDetector(
                  onTap: () {
                    context.read<TestBloc>().functionA();
                  },
                  child: Container(
                    padding: const EdgeInsets.all(8),
                    color: Colors.blue,
                    child: const Text('Click Function A'),
                  ),
                ),
              ),
              const SizedBox(height: 8),
              Container(
                alignment: Alignment.center,
                child: GestureDetector(
                  onTap: () {
                    context.read<TestBloc>().functionB();
                  },
                  child: Container(
                    padding: const EdgeInsets.all(8),
                    color: Colors.blue,
                    child: const Text('Click Function B'),
                  ),
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}

class TestBloc extends Cubit<int> {
  TestBloc() : super(0);

  void functionA() {
    print("Hello Function A");
    emit(state * 2);
  }

  void functionB() {
    print("Hello Function B");
    emit(state - 10);
  }
}