JPA Toplink, class cast exception when casting class A to class A

Question

I get a really strange exception from Toplink JPA. I used netbeans to create a persistence.xml and I generated a class (entity) from the table in a DB. Everything works fine, when I create a select query, I get the list of objects and the list is correctly typed. I can the objects in the list in debug mode with every field correctly set. But then I need to start working with the list, so I iterate through the list. And then I get ClassCastException from class A to class A (when A is the canonical name of the entity class).
I was working with JPA for some time but never seen that. I am using glassfish v2, mysql, netbeans 6.1. I could post the classes and persistence xml, but persistence.xml is really simple (no class definitions) and the class is annotated by netbeans. Every field is annotated like this:
@Column(name = "name", nullable = false)
And Date columns have
@Temporal(TemporalType.TIMESTAMP)
The whole class is annotated with @Table.
Does anyone has any idea, what can be wrong?

Answer 1

DrClap wrote:
Make sure your URLClassLoader cannot load the IAdapter class.
That is not exactly correct. He needs to make sure his URLClassloader has access to the IAdapter class. Sure, it should not load it on its own, but if requested the URLClassloader should be able to ask a parent to load IAdapter. Which in the end looks the same. But is not the same.
So set the parent classloader of your URLClassloader to a classloader capable of loading IAdapter.