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.
It would be helpful if you posted some sample code to look at. No need to give us the whole thing, just the area where the problem is. A complete stack trace helps too. (try to use the [ code] tags to format your code as well...)