FindBugs to Catch Bugs in your Java Code

I came across a free static bug finder called FindBugs today. Within just a few minutes of learning of it, I had downloaded the eclipse plugin and run it against an Android app I'm (hopefully!) close to finishing.  It had a few false positives, but it wasn't overly noisy.  It convinced me to change some inner classes to static ones, caught a potential null pointer exception, and got me to take a look at some borderline cases.   Looks like it hasn't had an update in a few years, but it's such an easy way to get another quick check of your code.  Definitely recommended.