Flutter Can';t将抽象类的子类型作为参数传递到函数中
我遵循了BloC教程,并按照他们所做的,我有一个BloC,它有这个方法Flutter Can';t将抽象类的子类型作为参数传递到函数中,flutter,dart,inheritance,bloc,Flutter,Dart,Inheritance,Bloc,我遵循了BloC教程,并按照他们所做的,我有一个BloC,它有这个方法 @override Stream<FridgeState> mapEventToState(FridgeEvent event) async* { .. } 在小部件中实例化bloc并传入FridgeEvent的子类时,我得到一个错误,即无法分配参数类型。我做错了什么 根据要求,这是集团的代码 import 'package:flutter_bloc/flutter_bloc.dart'; import
@override Stream<FridgeState> mapEventToState(FridgeEvent event) async* { .. }
在小部件中实例化bloc并传入FridgeEvent
的子类时,我得到一个错误,即无法分配参数类型。我做错了什么
根据要求,这是集团的代码
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:foodey_flutter/domain/fridge/entity/Fridge.dart';
import 'package:foodey_flutter/domain/fridge/usecase/CreateFridgeUseCase.dart';
import 'package:foodey_flutter/factory/FridgeFactory.dart';
import 'package:foodey_flutter/ui/fridge/create//event.dart';
import 'package:foodey_flutter/ui/fridge/create//state.dart';
class FridgeBloc extends Bloc<FridgeEvent, FridgeState> {
CreateFridgeUseCase? createFridgeUseCase;
FridgeBloc(FridgeState initialState) : super(initialState) {
FridgeFactory.inject(this);
}
@override
Stream<FridgeState> mapEventToState(FridgeEvent event) async* {
if (event is CreateFridgeEvent) {
Fridge? result = await createFridgeUseCase?.execute(event.lat, event.lng);
if (result != null)
yield FridgeSuccessfullyLoadedState(result);
else
yield FridgeErrorState(
exception: Exception("Failed to create a fridge"));
} else {
yield FridgeErrorState(exception: Exception("Operation not supported"));
}
}
}
更新:在复制粘贴代码并检查完整性后,我发现了问题。对于面临相同问题的任何人:在bloc代码中导入事件在路径中包含两个
/
。删除一个/
后,编译器不再抱怨传递了错误的类型。不知道第二个/
是如何添加的,也不知道为什么编译器根本没有对此抱怨。显然,从。//event.dart
导入时,在。//event.dart
中定义的对象不同。在复制粘贴代码并检查完整性后,我发现了问题。对于面临相同问题的任何人:在bloc代码中导入事件在路径中包含两个/
。删除一个/
后,编译器不再抱怨传递了错误的类型。不知道第二个/
是如何添加的,也不知道为什么编译器根本没有对此抱怨。
显然,从
。//event.dart
导入时,在。//event.dart
中定义的对象可能与导入时的对象不同。你能分享你的bloc文件和widget文件吗(导入的完整代码)?请提供一个。更新,谢谢提示
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:foodey_flutter/domain/fridge/entity/Fridge.dart';
import 'package:foodey_flutter/domain/fridge/usecase/CreateFridgeUseCase.dart';
import 'package:foodey_flutter/factory/FridgeFactory.dart';
import 'package:foodey_flutter/ui/fridge/create//event.dart';
import 'package:foodey_flutter/ui/fridge/create//state.dart';
class FridgeBloc extends Bloc<FridgeEvent, FridgeState> {
CreateFridgeUseCase? createFridgeUseCase;
FridgeBloc(FridgeState initialState) : super(initialState) {
FridgeFactory.inject(this);
}
@override
Stream<FridgeState> mapEventToState(FridgeEvent event) async* {
if (event is CreateFridgeEvent) {
Fridge? result = await createFridgeUseCase?.execute(event.lat, event.lng);
if (result != null)
yield FridgeSuccessfullyLoadedState(result);
else
yield FridgeErrorState(
exception: Exception("Failed to create a fridge"));
} else {
yield FridgeErrorState(exception: Exception("Operation not supported"));
}
}
}
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:foodey_flutter/ui/fridge/create/FridgeBloc.dart';
import 'package:foodey_flutter/ui/fridge/create/event.dart';
class CreateFridgeWidget extends StatefulWidget {
@override
_CreateFridgeState createState() => _CreateFridgeState();
}
class _CreateFridgeState extends State<CreateFridgeWidget> {
late FridgeBloc _bloc;
@override
void initState() {
super.initState();
this._bloc = BlocProvider.of<FridgeBloc>(context);
}
@override
Widget build(BuildContext context) {
return Container(
key: widget.key,
alignment: Alignment.center,
padding: EdgeInsets.all(8),
child: Column(
children: [
Text("Are you sure you want to create your fridge?"),
Row(
children: [
TextButton(
key: widget.key,
onPressed: () {
_bloc.add(CreateFridgeEvent(lat: 0, lng: 1));
},
child: Text("Yes"),
),
TextButton(
key: widget.key,
onPressed: () => {},
child: Text("No"),
),
],
)
],
),
);
}
}
abstract class FridgeEvent {
const FridgeEvent();
}
class CreateFridgeEvent extends FridgeEvent {
final double lat, lng;
CreateFridgeEvent({required this.lat, required this.lng});
}
class DeleteFridgeEvent extends FridgeEvent {}