Question

I have a problem here that still cannot solve, the thing is I have this abstract class:

public abstract class AbstractBean<T> {
    private Class<T> entityClass;

    public AbstractBean(Class<T> entityClass) {
        this.entityClass = entityClass;
    }
    ...
}

Now I have another class that inherits this abstract:

@Stateless
@LocalBean
public class BasicUserBean<T extends BasicUser> extends AbstractBean<T>  {
    private Class<T> user;    

    public BasicUserBean() {  
        super(user);  // Error: cannot reference user before supertype contructor has been called.
    }
}

My question is how can I make this to work?, I am trying to make the class BasicUserBean inheritable, so if I have class PersonBean which inherits BasicUserBean then I could set in the Generic the entity Person which also inherits the entity BasicUser. And it will end up being:

@Stateless
@LocalBean
public class PersonBean extends BasicUserBean<Person>  {

    public PersonBean() {
        super(Person.class);
    }
    ...
}

I just want to inherit the basic functionality from BasicUserBean to all descendants, so I do not have to repeat the same code among all descendants. Thanks!.

Answer 1

You need to add the constructor to BasicUserBean taking a Class<T>

public BasicUserBean(Class<T> entityClass) {
    super(entityClass);
}

Your no argument constructor won’t work since the class you’re extending requires a T. You can’t have a T in your constructor without taking in a T as an argument; not without a cast anyway.