Java support for KDE is now fairly significant, you can add applet support to your KDE applications, and with the Qt/KDE Java bindings you can even develop KDE apps in Java. Issues relating to Java support for KDE should be discussed on the kde-java mailing list (though applet issues are usually discussed on kfm-devel).
- QtJava and KDEJava (Koala)
The QtJava and KDEJava (Koala) bindings developed by Richard Dale allow you to create Qt and KDE applications using Java. The code uses JNI to allow Java code to access KDEs native widgets. These bindings can be found in the kdebindings module of the KDE Subversion repository (Instructions).
- KDE Java Applet Server (KJAS)
KJAS allows KDE applications to embedd Java applets. It uses a pure Java server to run the applets, which it communicates with using standard UNIX pipes. KDE programmers can use a special KJavaAppletWidget to display the applets in their application. KJAS is already in a usable state.
The QtAWT is a port of the peer classes underlying the Java AWT to the Qt toolkit, in future it will also use the KDE widgets. QtAWT is currently very incomplete, but you should feel free to give it a try, or even better to help finish it.
- Mailing List (Archives)
There is a dedicated mailing list for Java-specific issues in KDE. It is a fairly low-traffic list aimed at developers with an interest in writing Java applications for KDE and/or writing and maintaining the Java bindings.