在另一个类中注入一个类对象而不将它添加到构造函数中

Question

I have a Handler class in which I am using lombok to inject the dependencies and create the required args constructor. The class looks like below:

@RequiredArgsConstructor(onConstructor = @__(@Inject))
class Handler {
  private final @NonNull ObjectMapper objectMapper;
  private final @NonNull UserAddressBookDao userAddressBookDao;

  //Some methods below
}

Now I have to include/inject another class ie Controller class object in the handler class so the updated handler class would be:

@RequiredArgsConstructor(onConstructor = @__(@Inject))
class Handler {
  private final @NonNull Mapper mapper;
  private final @NonNull UserDao userDao;
  //newly added class member
  private final @NonNull Controller controller;

  //Some methods below ...'
}

I don't want the new class member in the constructor since I have used handler class at a lot of places in my service that If I add a new class member I would have to update code at all those places to add the new member into the constructor. I want the new member to be excluded from the Handler class's constructor so that I can avoid this situation. Also the controller class has a lot of members since initializing it will be a problem if I would try to at the required places. So, is there anyway I can inject Controller into my handler class without including that in the constructor. Thank you so much in advance and please forgive if the question sounds too vague. The controller class looks like this:

@Singleton
@RequiredArgsConstructor(onConstructor = @__(@Inject))
public class Controller {

    @NonNull
    private final ABCService abcClient;
    @NonNull
    private final DdbDao DdbDao;
    @NonNull
    private final ServiceAccessor serviceAccessor;

    `Some methods below ...`

Answer 1

• Firstly you have to remove @NotNull annotation and final modifier from Controller field, as lombok will pick it up for @RequiredArgsConstructor .
  final should be removed anyway, as compiler requires it to be assigned by the constructor and you specifically don't want to set it in a constructor .
  If you want to keep @NotNull then look and lombok 's @SomeArgsConstructor where you define explicitly which arguments will be set by the constructor.
• then add @Inject annotation to the setter for controller:
  @Inject public void setController(Controller controller) {this.controller = controller;}
  ... so it can be inhjected by guice outside of the constructor.