Cubit
- Flutter course
- Intermediate
- Lesson 17/99
- 4 min
Build a simple state class with Cubit.
Cubit
Cubit is the simpler class of the Bloc package. Instead of event classes, you call methods directly; you publish new state with emit.
class CounterCubit extends Cubit<int> {
CounterCubit() : super(0);
void increment() => emit(state + 1);
}Cubit requires less code than Bloc for simple state.
Changing state with emit
Inside a Cubit, calling emit(newValue) publishes the new state. The state property gives the current state.
void increment() => emit(state + 1);
void decrement() => emit(state - 1);When emit is called, all listening widgets update.
Practice Build a counter with Cubit
Make SayacCubit extend Cubit<int>. Set initial state to 0 with super(0). The artir method should call emit(state + 1). In main, create a Cubit instance, call artir and print with print('deger: ${cubit.state}').
Starter code
import 'package:flutter_bloc/flutter_bloc.dart';
// SayacCubit, Cubit<int>'ten türetilsin
void main() {
final cubit = SayacCubit();
cubit.artir();
print('deger: ${cubit.state}');
}Sample solution
import 'package:flutter_bloc/flutter_bloc.dart';
class SayacCubit extends Cubit<int> {
SayacCubit() : super(0);
void artir() => emit(state + 1);
}
void main() {
final cubit = SayacCubit();
cubit.artir();
print('deger: ${cubit.state}');
}Expected output
deger: 1
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the difference between Cubit and Bloc?
- Does not publish state
- Runs slower
- Only works with StatelessWidget
- Uses method calls instead of event classes Correct answer
Explanation: Cubit does not define event classes like Bloc; it changes state directly via method calls and publishes new state with emit.
2 Complete the emit call inside Cubit
class SayacCubit extends Cubit<int> {
SayacCubit() : super(0);
void artir() => ____(state + 1);
}class SayacCubit extends Cubit<int> {
SayacCubit() : super(0);
void artir() => emit(state + 1);
}Explanation: In Cubit, emit is called to publish new state; this updates listening widgets.
3 Cubit parts
| Term | Meaning |
|---|---|
Cubit |
Simple-state Bloc class |
emit |
Method to publish new state |
state |
Current state value |
super(0) |
Initial state |