This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
It's not an error; it's a warning. You can safely ignore it, but it's telling you that there's a better way to do something that you're doing. It's also telling you how to find out more about what specifically the problem is: add "-deprecation" to your "javac" command line, and it will tell you specifically what deprecated API you're overriding.
"Deprecated" basically just means "being replaced by something better."