JPA with EclipseLink, error Entity cannot be cast to Entity, any help?

Question

Hello, I'm currently deploying a JPA project with EclipseLink on a MySQL db, it's been working fine, however, I'm receiving a problem of this type:
java.lang.ClassCastException: beans.Empleado cannot be cast to beans.Empleado
Where Empleado is my Entity, basically the problem happens here, where I store a result from a SQL select into a List and then assign the results into variables, it was working with no problems before, but now, everytime I run the code, the error shows up, and the only way to make it work at least 2 - 3 times, is restarting the Glassfish Server, here's the code:
Query q = em.createNamedQuery("Empleado.findByIdEmpleado");
q.setParameter("idEmpleado", 2);
List<Empleado> listaEmpleado = q.getResultList();
for(Empleado empleado1 : listaEmpleado){
testString = empleado1.getTecnologia();
But as I said, it was working fine before, so I don't think is actually a code problem, I guess the "cast" reference is happening here:
for(Empleado empleado1 : listaEmpleado)
The errors shows up with every function where I make this kind of casting......
As a comment, I have a similar project at home, and I don't have these problems, this is happening on a project at work, but both project are the same, it's just I'm doing this one at work and the other at home, which is working fine, thanks in advanced, have a nice day, I just hope I was clear about this!
Edited by: user3538005 on 08-11-2011 09:08 AM

Answer 1

Hola,
It's quite strange stuff :) Mainly the exception, beans.Empleado cannot be cast to beans.Empleado.
I think it's because of some configuration problem, related to classloader:
EclipseLink has it's own classloader, if your beans.Empleado is loaded by EclipseLink's classloader, and by a different one (default classloader), you will have two beans.Empleado classes in your JVM, and these classes are different, so you cannot cast them :O
so your eclipselink's classloader has its beans.Empleado(1) class, and after executing your query you have a list with the results each of them in beans.Empleado(1).
and your dao class, or whatever, tries to cast the beans.Empleado(1) to the default classloader's beans.Empleado(2).
what did you change in the config when it started not to work?