I notice my fedore core 4 has eclipse allready installed and compiled. I also notice that I have gcj installed instead of sun java.
When I tried to compile a trivial hello world java program, I get the a stack trace (see below). I noticed that JAVA_HOME was not defined so I did "export JAVA_HOME=/usr/bin" which is where it seemed to be.
However, I know java (gcj) is working correctly because the following works:
JAVA_HOME points to the root directory of the JDK.
I personally find the "alternatives" system to be a royal pain when working with Java. But in any event, I don't think that the gcj system is complete enough to run Eclipse. I recomend downloading a Sun (or IBM) jdk, installing it, and pointing JAVA_HOME at the installed Java.
An IDE is no substitute for an Intelligent Developer.