(http://c2.com/ppr/wiki/JavaIdioms/html.zip -- fast download of all these pages.)
Java 5 Idioms
The word 'Idiom', in this context, should be taken to mean something like 'Common Practice'. This page isn't an appropriate place to put patterns, it's a place to put example of common solutions to java coding problems. If the Idiom linked to off this page has no code, then its a pattern. If its about using a related group of classes to solve a design problem, then it is a pattern too.
Caveat: read the reviews on Amazon to check that the above two books are aimed at your level of experience. Also, you can find several of the patterns in these books, and the upcoming volume 3, on this page and elsewhere on the WikiWikiWeb. Volume 3 is out and claims to cover J2EE design patterns.