There is a very good tool -[url=http://fem.um.es/Ejs/Ejs_en/index.html]Easy java Simulation [/url]- can help you create java simulation much easier. There are a lot of examples in the distribution. Several java applets on this site are created again with easy java simulation and can be found in the distribution, too. (Under Simulations/_examples/FuKwunHwang) I will send source code to your email address.