抽象类无法实例化！在 AuthenticationBloc 中答案

【问题标题】：Abstract class can't be instantiated! in AuthenticationBloc抽象类无法实例化！在 AuthenticationBloc 中
【发布时间】：2021-06-11 22:29:32
【问题描述】：

AuthenticationBloc 的屏幕截图

如何处理这些错误？

这是我的身份验证状态。

part of 'authentication_bloc.dart';

@immutable
abstract class AuthenticationState extends Equatable {
  //
  final AuthenticationStatus status;
  final User user;

  AuthenticationState._({
    this.status = AuthenticationStatus.unknown,
    this.user = User.empty,
  });

  AuthenticationState.unknown() : this._();

  AuthenticationState.authenticated(User user)
      : this._(status: AuthenticationStatus.authentidated, user: user);

  AuthenticationState.unauthenticated()
      : this._(status: AuthenticationStatus.unauthenticated);

  @override
  List<Object> get props => [status, user];
}

【问题讨论】：

你能显示你的AuthenticationState吗？
嗨，我已经添加了 AuthenticationState。

标签： flutter dart bloc flutter-bloc

【解决方案1】：

也许您想使用单个状态，为此您需要从状态类声明中删除 abstract 关键字。你可以使用

注意类不是抽象的

part of 'authentication_bloc.dart';

@immutable
class AuthenticationState extends Equatable {
  //
  final AuthenticationStatus status;
  final User user;

  AuthenticationState._({
    this.status = AuthenticationStatus.unknown,
    this.user = User.empty,
  });

  AuthenticationState.unknown() : this._();

  AuthenticationState.authenticated(User user)
      : this._(status: AuthenticationStatus.authentidated, user: user);

  AuthenticationState.unauthenticated()
      : this._(status: AuthenticationStatus.unauthenticated);

  @override
  List<Object> get props => [status, user];
}

【讨论】：

【解决方案2】：

您的AuthenticationState 是一个抽象类。所以你不能实例化它，这意味着你不能从它创建一个对象。要解决此问题，请省略 abstract。
我对Bloc 非常熟悉，我建议您为每个状态创建一个新类并从 AuthenticationState 扩展。

@immutable
abstract class AuthenticationState extends Equatable {
  final AuthenticationStatus status;
  final User user;

  AuthenticationState({
    this.status = AuthenticationStatus.unknown,
    this.user = User.empty,
  });

  @override
  List<Object> get props => [status, user];
}

class AuthenticationStateUnknown extends AuthenticationState {
  AuthenticationStateUnknown() : super();
}

class AuthenticationStateAuthenticated extends AuthenticationState {
  AuthenticationStateAuthenticated(User user)
      : super(status: AuthenticationStatus.authenticated, user: user);
}

class AuthenticationStateUnAuthenticated extends AuthenticationState {
  AuthenticationStateUnAuthenticated()
      : super(status: AuthenticationStatus.unAuthenticated);
}

【讨论】：