Angular 提交UserEditComponent后角度可观测UserListComponent自动更新

如何刷新已由UserListComponent中的UserEditComponent编辑的用户，而不是重新加载所有用户？以下是相关代码：

在user.service.ts中：

class UserService with update（user:user）：void{…}

在user-edit.component.ts中：

class UserListComponent {
  users: Observable<User[]>;
  ngOnInit(): void {
    this.users = this.userService.users;
    this.userService.loadAll();
  }  
}

class UserEditComponent with submit（）：void{…}

在user-list.component.ts中：

class UserListComponent {
  users: Observable<User[]>;
  ngOnInit(): void {
    this.users = this.userService.users;
    this.userService.loadAll();
  }  
}

UserListComponent的HTML：

                <mat-list-item *ngFor="let user of users | async">
                    <h3 mat-line>
                        <a mat-button [routerLink]="['/user-edit', user.id]">{{user.person.firstName}} {{user.person.middleName}} {{user.person.lastName}}</a>
                    </h3>
                </mat-list-item>

UserEditComponent具有：

users: Observable;
  ngOnIinit(): void {
  users = this.userService.users;
  this.userService.loadAll();
}

  user: Observable;
  form: FormGroup;
  submit(): void {
    if(this.form.valid) {
      this.userService.update(this.form.value);
      this.gotoList();
    }
  }

  gotoList(): void {
    this.router.navigate(['/user-list']);
  }