java - JPA doesn't support interfaces well..implications?

Question

I was going through some posts in Stackoverflow on JPA and I read multiple places that JPA does not support interfaces. Can someone please share what it means in a real-world project. Does this mean we cannot annotate the interface?

Answer 1

What this means is that you cannot map (annotate) or query on an inferface. You can only query @Entity classes, and these can only be placed on real classes, not interfaces. Normally this is not an issue, an interface has no state, so is not something that is really relevant to persistence most of the time. You can still use interfaces in your model, you just can't map them directly.

If you have a relationship that uses an interface type, you just need to set the targetEntity to the implementation class. If you have multiple implementers and can't make them share inheritance then you need to get more creative. Some JPA providers such as EclipseLink have support for interfaces.

See, http://en.wikibooks.org/wiki/Java_Persistence/Advanced_Topics#Interfaces