Flutter，一个小小的 Cubit BlocBuilder 问题

Question

我正在尝试使用 BlockBuilder 显示我的 Cubit 的 int 状态，这是我的代码：

class CounterCubit extends Cubit<int> {

  CounterCubit() : super(0);
  void increment() => emit(state + 1);
  void decrement() => emit(state - 1);
}

class CounterContainer extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(create: (_) => CounterCubit(), child: CounterView());
  }
}

void main() {
  runApp(MaterialApp(
    theme: myTheme,
    home: CounterView(),
  ));
}

class CounterView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;
    return Scaffold(
      appBar: AppBar(
        title: const Text("Example"),
      ),
      body: Center( //I guess the problem is here
          child: BlocBuilder<CounterCubit, int>(builder: (context, state) {
          return Text("$state", style: textTheme.headline2);
      })),

      //Increment and decrement button
      floatingActionButton: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        crossAxisAlignment: CrossAxisAlignment.end,
        children: [
          FloatingActionButton(
            child: const Icon(Icons.add),
            onPressed: () => context.read<CounterCubit>().increment(),
          ),
          const SizedBox(
            height: 8,
          ),
          FloatingActionButton(
            child: const Icon(Icons.remove),
            onPressed: () => context.read<CounterCubit>().decrement(),
          )
        ],
      ),
    );
  }
}

控制台错误是

错误：在此 BlocBuilder 小部件上方找不到正确的提供程序

我已经尝试过使用 Provider 但它不能解决问题

Answer 1

你没有使用CounterContainer，所以你没有CounterCubit。 应该是：

void main() {
  runApp(MaterialApp(
    theme: myTheme,
    home: CounterContainer(),
  ));
}