This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
the problem comes when I try to execute any of the entity manager methods, such as persist() or find(). It always throws a NullPointerException so I'd like to know where could be my problem. Any idea will help.
Thanks in advance