Finally I have got around to releasing version 5.0 beta 1 of Checkstyle. This release is built on Java 5 for Java 5 (and above). There are new Checks for Java 5 and numerous bug fixes. See more details at

The source code has been converted over to use Java 5. It has been interesting to use Java 5 in anger and I have learnt a bit (which was the motivation). I do like the way Google Collections helps reduce the amount of noise that comes from Generics. My favourite Java 5 language feature to date without a doubt is annotations.