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.
This has been asked and answered exhaustively many, many times. Please use the "Search" link at the top of the page to find the previous discussions. Make sure you search through all forums, not just this one.