Annotations: extending a superclass that has no annotations

elmosca · **Joined:** Mon Mar 14, 2005 4:16 pm **Posts:** 27

Hi,

I have a question related with annotations and polymorphism where the superclasses has no annotations at all. I would like to extend to existent classes (not persistent) with persistent subclasses (with annotations). Let's imagine this situation:

I have two superclasses, one of those uses the other

Code:

public class Driver {
}

public class Car {
      public Driver getDriver() {}
}

I would like to create to extend those two classes with persistent ones, let's say

Code:

@Entity
...
public class PersistentDriver extends Driver {
}

@Entity
public class PersistentCar extends Car {
    // THIS SHOULD RETURN A PERSISTENT DRIVER
     public Driver getDriver(){}
}

But, when registering the annotated classes in the

Code:

AnnotationConfiguration

, I get the exception

Code:

Could not determine type for: Driver

...
So, it is possible to subclass from classes that have not annotated attributes? Is there a way to return the Driver by using the PersistentDriver class?

Thanks in anticipation,

Bruno

jlowcock · **Joined:** Thu Apr 07, 2005 6:09 pm **Posts:** 3

I have experienced a similar issue when I have interfaces rather than your concrete base classes which are not @Entity classes. I would like to develop to the interfaces and implement to the @Entity beans. However in my tests I receive the same exception.

elmosca · **Joined:** Mon Mar 14, 2005 4:16 pm **Posts:** 27

With entities implementing interfaces you can use the parameter targetEntity in your one-to-manies, etc and it sould work ok... What I found after some test is that when you implement a base class (e.g. the getDriver method) you can put the @Transient annotation in the base method. However this creates a dependency with the base class and Hibernate and this is something I wanted to avoid. Is this expected behaviour?

Bruno

emmanuel · **Posted:** Tue Apr 12, 2005 6:36 am

elmosca wrote:

However this creates a dependency with the base class and Hibernate and this is something I wanted to avoid. Is this expected behaviour?

Bruno

This will change when the new EJB3 spec draft will be out.