How does polymorphism="explicit" work? Does this enable only base class loading and instantiation?

If I have
Class A {
}
Class B extends A {
}

And when I set explicit polymorphism

<class name="A" table="a" polymorphism="explicit">

</class>

<joined-subclass name="B" table="b">

</joined-subclass>

If I use A.class with Criteria, I am getting instnace of B. Is there a way to get only instance of A. And get B only when I specify B.class?

If you specify the superclass, you will get all subclasses. If you specify a subclass, you will get only those subclasses.

I don't know of a way to only get the superclass objects.

I believe the assumption here is that the superclass is abstract and isn't used by itself.

Honestly, I've been frustrated by this at times... but when it comes down to it, I find that I'm doing something lame when I need to query concrete instances of a base class directly. When I need that, I tend to go ahead and create an abstract base class and two subclasses.

If A extends B, then asking for all the B's which aren't A's is essentially like doing instanceof in hql.

To answer the question you actually asked, I believe polymorphism="explicit" does actually work, but then you won't be able to query for all of the B's and A's in one shot... I definitely prefer the abstract base class approach.

I think you're correct that it works fine for <subclass> but <joined-subclass> works a bit differently.