Most of you already know how to compile and run Java programs, and there's nothing special to be done for multithreaded programs. Version 1.4 of Java 2 is installed in /usr/local/java/bin, which should already be in your search path. If you want to try out the new features of version 1.5, a copy is installed in /users/mlewis/jdk1.5.0/bin. You can add this to your search path, or define aliases for the compiler and JVM like this:
alias newjavac=/users/mlewis/jdk1.5.0/bin/javac
alias newjava=/users/mlewis/jdk1.5.0/bin/java
Put these lines in your .bashrc file (or the equivalent if you use csh) to have the aliases defined every time you log in.
Interesting machines to run on are the Dwarf machines (Dwarf1 through Dwarf7), which have two processors each, and SnowWhite, which has four processors.