catch ConstraintViolationException - doesnt work

I am unable to catch ConstraintViolationException

public BigDecimal createSubBoard(SubBoard subBoardObj, Users user) {
EntityManager em = EMFUtility.getEntityManager();     
EntityTransaction et = null; 
SubBoards subBoard = null;
SubBoard subBoards = null;
Boards board = null;
BigDecimal subBoardId = new BigDecimal(0);
try {
logger.debug(" #### BoardsDao - createSubBoard"+subBoardObj.toString());
et = em.getTransaction();
et.begin();
try{
subBoardObj.setCreateDate(new Date());
subBoardObj.setCreatedBy(user.getEdipi());
em.persist(subBoardObj);
subBoardId = subBoardObj.getId();
et.commit();
} catch(EJBTransactionRolledbackException  ce) {
System.out.println("!!!");
Throwable t = ce.getCause();
while ((t != null) && !(t instanceof ConstraintViolationException)) {
t = t.getCause();
}
if (t instanceof ConstraintViolationException) {
System.out.println("...........");
// Check here if the delete date is also null
}
}   
///TODO..///	
} catch (Exception e) {
et.rollback();
e.printStackTrace();
System.out.println("!!!! "+e.getCause() );
logger.debug(" #### BoardsDao - createSubBoard :Exception is " + e.getMessage());
throw new PersistenceException("Error persisting entity in createSubBoard "+ e.getMessage());
} finally {
em.close();
} 
return subBoardId;
}

in this code em.persist(subBoardObj); throws ConstraintViolationException. I tried using getCause() and identify if constraintViolation but the code control doesnt goto that catch block. It goes to generic Exception block. Can someone suggest whats wrong.

First of all, I would not recommend doing transaction handling manually but instead use declarative transaction management. If you use EJBs, you just need to annotate the bean as @Stateless or if you want to change the transaction demacration strategy use the @TransactionAttribute annotation on the method. If you really must use manual transaction management you should use the UserTransaction interface. This is because EJB works with the JTA specification which you probably also configured as transaction strategy in your persistence unit.

Having said that, EntityManager.persist and EntityManager.flush throw javax.persistence.PersistenceException that wrap a org.hibernate.exception.ConstraintViolationException. So you need to catch the PersistenceException and then use getCause to get the constraint violation.