The JDK does not support directly editing class files. There are a number of third-party tools that do support this -- Google is your friend. Now two questions for you: 1) Why JDK 1.2.2 -- it's ancient! Newer Linux JDKs have much better performance. 2) Do you really mean "editing class files" or are you just trying to say "writing or editing code?" If it's the latter, most Linux distributions contain many suitable text editors, perhaps including Emacs, vi, nedit, kedit, kate, and others, any of which can be used to edit Java code.