Isn't the 5.0 java compiler really labelled version 1.5? I could be wrong, but thats what I thought.
Edit: NOTE: The Java version numbering scheme is a bit of a mess, thanks to the geniuses in Sun's marketing department. Java 5 is internally numbered as 1.5. In fact, the various versions of Java are officially named Java 1.0, Java 1.1, Java2 SE 1.2, Java2 SE 1.3, Java2 SE 1.4, Java2 SE 5.0, Java SE 6. The SE denotes the “standard edition”. There is a micro edition (ME) for cell phones and other small devices, and an enterprise edition (EE) for servers
From http://www.horstmann.com/bigj/help/compiler/tutorial.html