Problems with Injection (Using vaadin)

Question

I am newbie with EJB and Injections...

I am currently using Vaadin framework with CDI

I have been trying to using injection but i have not could do it...

In my Vaadin UI class MyVaadinUI i have tried...

CDIUI("")
@SuppressWarnings("serial")
public class MyVaadinUI extends UI {


@EJB
UserController userController;

@Override
protected void init(VaadinRequest request) {

  System.err.println("desde controller "+userController.getAll().size());

}

}

UserController

@Stateless
public class UserController {

    @EJB
    IUserDAO userDao;

   public List<User> getAll() {

        return userDao.findAll();
    }


}

and it works!!

but when I do not inject UserController, it does not work... In other words when I instance the class UserController the injection in this class does not work...

Code does not work

     CDIUI("")
    @SuppressWarnings("serial")
    public class MyVaadinUI extends UI {


    @Override
    protected void init(VaadinRequest request) {
           UserController userController = new UserController();
      System.err.println("desde controller "+userController.getAll().size());

    }

}

Somebody can explain me why?

Thanks

Nicolas

Answer 1

Only in injected objects will have its dependencies injected. If you create an object with new all field having @inject, @ejb or @resource will not be injected. In your case you create UserController like this:

UserController userController = new UserController();

and so this field will not be injected:

@EJB
IUserDAO userDao;

And therefore getAll() will throw a NullPointerException.

I use vaadin and cdi for projects. I'd recommend to use injection for almost everything or not at all. I inject my uis, views, own components... (and do not create them with new) so it is possible to inject ejb beans or other things into them. If you are using it only sometimes you are ending up with am mixture of injection and normal object creation and will have to pass around injected objects to other object you instantiated yourself. In another project of mine this happened and got really problematic for future changed in the code.