Re: MappedSuperClass annotation

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.help

Date:

Fri, 27 Jan 2012 19:24:15 -0800

Message-ID:

<jfvpov$g19$1@news.albasani.net>

Daniel Pitts wrote:

Lew wrote:

Pidi wrote:

If an abstract class inherits from an abstract superclass annotated with
@MappedSuperclass, it inherits the annotation too or if I want both
annotated
I have to replicate the annotation?

Ex:
@MappedSuperclass
public abstract Class1 {
...
}

@MappedSuperclass <-- I have to declare it or it's implicit?
public abstract Class2 extends Class1{
...
}

You have to declare it. Annotations do not inherit.

True, and that annotation specifically needs to be declared everywhere you
want the effect.

In general though, it is up to the framework which utilizes the annotations to
decide if they want to climb up the inheritance or not.

Good point, but I couldn't come up with an example that does, and certainly
none for JPA.

This is at least hinted if not evident from the documentation, for example:
<http://docs.oracle.com/javaee/6/tutorial/doc/bnbqn.html>
in which the very introduction of entities shows the need to repeat the
'@Entity' annotations at each level of inheritance.

That said, the need for multiple levels of inherited '@MappedSuperclass'
annotated types should be vanishingly rare. There's a very, very good chance
that the OP should *STOP* what they're doing and reconsider, then get rid of
the idea. I cannot even think of a scenario where it would help. It goes
firmly against the intended purpose of that annotation.

--
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg