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.
In general, you don't need to worry about garbage collection in Java. The JVM contains very sophisticated algorithms to make garbage collection as efficient as possible, and you are probably not going to gain much by trying to optimize it.