How to handle JPA annotations for a pointer to a generic interface

Question

I have a generic class that is also a mapped super class that has a private field that holds a pointer to another object of the same type:

@MappedSuperclass
         


        

Answer 1

My problem is that Eclipse is showing an error in the file at the OneToOne "Target Entity "T" for previous is not an Entity."

Yes, and even if T was extending an Entity, I am not aware of any JPA provider supporting this (that's just not part of the JPA spec anyway). For more feedback have a look at JPA Generic entities classes Mappedsuperclass are not possible! (very similar thread about EclipseLink):

No you will be unable to make the Entities generic. The provider will be unable to map the relationship to the specific type defined by the generic definition as this type is assigned when the Entity is created in code not where the Entity is defined. Remember when designating Generics the Collection (in this case) is limited only to those types. The Provider can not possibly be this restrictive on a per Entity instance basis. In some cases changing the type may result in entirely different tables being mapped for a single Entity instance and that is definitely not supported.