Java 1.6 has some nice new classes, in particular some useful additions to the concurrent collections packages like ConcurrentSkipListMap. The problem? I’m stuck with Java 1.5 because I use OSX 10.5 on a Mac, and Java 1.6 isn’t properly supported yet (curse you Jooooobs!).

Anyway, only slightly daunted, I made my own using the source code from the original JSR166 proposal (which is public domain – no licensing headaches).

Find the jar file here: jsr166x.jar.