Unit testing is extremely useful. I'm working through this excellent guide : Pragmatic Programmer: Unit Testing in Java with junit I have yet to find any good websites for junit, but the book is great. I've had a lot of success in some small projects, using NetBeans 6.1 to generate empty tests for each class member. Then you go and fill them in. It's helping me to refresh my memory about the code and great to think of new ways to test the code and new ways to write the code.