jikes for fast java

I've been checking out ECJ, evolutionary computing in Java. They recommend using jikes instead of javac for faster compiles.

Here's the error I get and the answer:

*** Semantic Error: You need to modify your classpath, sourcepath,
bootclasspath, and/or extdirs setup. Package "java/lang" could not be found
in: .

What does that mean?

A:
The instructions are in the online notes, but not easy to find. Here's what you are looking for:

You probably want to use jikes instead of javac. It gives somewhat clearer error messsages, and it's about 10 times as fast. To use jikes, you need to do a little setup. Type the command

setenv CLASSPATH .:/s/jdk1.4.2/jre/lib/rt.jar



link