Hy have a little test class. I have the following line to load the "hibernate.cfg.xml":

SessionFactory sf = new Configuration().configure().buildSessionFactory(); <<<-----
session = sf.openSession();
tx = session.beginTransaction();

Mp mp = new Mp();
mp.setLegislacao("xpto");
session.save(mp);

tx.commit();
session.close();

He does all the mappings and associations, but right at the end of the above line (<<<----), he gives me:

Exception in thread "main" java.lang.NullPointerException
at pt.comseal.arsol.bo.mp.Maptest.main(Maptest.java:40)

Is he finding my "hibernate.cfg.xml"?

Please help.

Perhaps try this:

Failing that. Check the FAQ's at:
Hibernate Users FAQ

-G