> Run a 'which java' command to see exactly what java are you running,
> followed by 'java -version'.
>
> I suspect you did not get the SUN jdk but the GNU java.


[root at blh ~]# which java
/usr/bin/java
[root at blh ~]# java -version
java version "1.4.2"
gcj (GCC) 3.4.3 20050227 (Red Hat 3.4.3-22.1)


Bingo... I'm not sure how far along gcj is, but for the vast majority
of Java applications you'll need one of the Sun or IBM SDKs.    I
don't know much about your distro, but I'd you're usually better off
going to java.sun.com and downloading java 5 (a.k.a. 1.5.x) and
getting one of their RPMs.

As to the classpath, you can do a 'printenv CLASSPATH' to check it.  
If nothing shows up, google "bashrc CLASSPATH" and you should get
detailed instructions.