go to http://java.sun.com/products/archive/j2se/1.4.2_03/index.html
download the SDK *NOT* the JRE, also download the rpm version
under /etc/profile.d create a file "java.sh" and add to it the following :
export JAVA_HOME="/usr/java/j2sdk1.4.2_04"
export JAVA_PATH="$JAVA_HOME"
export JDK_HOME="$JAVA_HOME"
export PATH="$PATH:$JAVA_HOME/bin"

then type "java xxx.class" or "javac xxx.java" if you need to compile from src.
but if you have a large project y'll probably need ant or maven
but thats another story, so if you need help with'em just holler :)

AMG. -When things have gone from bad to worse, The cycle will repeate itself.

Dag Wieers has j2re in his repository: http://www.fedorafaq.org/#java

to compile java object code "javac xxx.java" and to run the class generated .. "java xxx " and any other arguments 'll be entered if needed ... depends on your code