Java is installed in various versions. They can be found under /usr/bin/java. As default we use Java 1.6.0_18 at the moment.
The Java-IDE Eclipse can be started using the command eclipse-3.2, eclipse-3.3 or eclipse-3.5.2 The reason for that is that there is a software ECLiPSe Constraint Logic Programming System with the same name.
Editor
On the pool computers there are different editors installed, among other things the quite mighty editors GNU Emacs and XEmacs.