Can i passing nothing in BlocBuilder with if else statement - flutter

Question

I don't want to pass data to text widget if the counterValue number is less than 0. This the code:
main.dart :
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_bloc_concepts/cubit/cubit/counter_cubit.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return BlocProvider<CounterCubit>(
create: (context) => CounterCubit(),
child: const MaterialApp(
title: 'flutter_bloc Demo',
debugShowCheckedModeBanner: false,
home: HomePage(),
),
);
}
}
class HomePage extends StatefulWidget {
const HomePage({Key? key}) : super(key: key);
#override
State<HomePage> createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Flutter BLoC Concepts DEMO")),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
const Text("You have pushed the button this many times:"),
// Bloc Builder
BlocBuilder<CounterCubit, CounterState>(
builder: (context, state) {
if (state.counterValue < 0) {
return NOTHING;
} else {
return Text(
state.counterValue.toString(),
style: Theme.of(context).textTheme.headline4,
);
}
},
),
const SizedBox(height: 20),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
FloatingActionButton(
onPressed: () {
BlocProvider.of<CounterCubit>(context).decrement();
},
tooltip: "Decrement",
child: const Icon(Icons.remove),
),
FloatingActionButton(
onPressed: () {
BlocProvider.of<CounterCubit>(context).increment();
},
tooltip: "Increment",
child: const Icon(Icons.add),
),
],
),
],
),
),
);
}
}
counter_cubit.dart :
import 'package:bloc/bloc.dart';
import 'package:meta/meta.dart';
part 'counter_state.dart';
class CounterCubit extends Cubit<CounterState> {
CounterCubit() : super(CounterState(counterValue: 0));
void increment() => emit(CounterState(counterValue: state.counterValue + 1));
void decrement() => emit(CounterState(counterValue: state.counterValue - 1));
}
counter_state.dart :
part of 'counter_cubit.dart';
class CounterState {
int counterValue;
CounterState({
required this.counterValue,
});
}
Can i pass nothing to text widget when counterValue number is less than 0. I don't want to show negative numbers, so if I press the decrement button when counterValue = 0 the number displayed is not negative -1,-2... / I want stay at 0. Can i do that

Answer 1

adding if else statement in counter_cubit.dart :
void decrement() {
if (state.counterValue <= 0) {
state.counterValue = 0;
} else {
emit(CounterState(counterValue: state.counterValue - 1));
}
}