I'm getting the same problem too.

I went to the sun site and apparnetly got JRE 1.4.1 installed (its in my usr/java/jre-1.4.1_02 folder)

After that I opened up Konsole:
[mike@localhost mike]$ which java
which: no java in (/usr//bin:/bin:/usr/bin::/usr/local/bin:/usr/X11R6/bin:/usr/games:/home/mike/bin)

and I got the same "readonly variable" error as tio

I'm running Mandrake 9.1 in KDE 3.1.0