I'm a total nubie. I thought it would be useful to download the source for an applet and study the code. I picked a wonderful applet by Don Hatch:
http://www.plunk.org/~hatch/HyperbolicApplet/?size=513. The code in the jar file is all in .prejava files. My IDE (NetBeans) doesn't know what to do with these files. When I rename the extension of the main class source from .prejava to .java I get a lot of errors. Can anyone help me understand what .prejava files are and how to work with them?