Angular 4调用2个组件

Question

我有两个组成部分：

UserComponent：

export class UserComponent {

@ViewChild(ProfileComponent)
profileComponent:ProfileComponent;

constructor(private userService: UserService, private confirmationService: ConfirmationService,private messageService: MessageService) {}
}

ProfileComponent：

export class ProfileComponent {

@ViewChild(ProfileComponent)
userComponent: UserComponent;

constructor(private profileService: ProfileService, private confirmationService: ConfirmationService,private messageService: MessageService) {}
}

我想在UserComponent中使用ProfileComponent并在ProfileComponent中使用UserComponent，但它无效。