#replace the java version name for the one you have downloaded
#This have worked for me:

1. Download jre-6u27-linux-i586.bin from the SUN site.
2. su-->pwd-->mv jre-6u27-linux-i586.bin to /usr/local
3. chmod u+x jre-6u27-linux-i586.bin
4. verify permissions: ls -l
5. ./jre-6u27-linux-i586.bin
6. Do you agree? Yes.-->Done
7. It's installed under: /usr/local/jre1.6.0_27
8. cd ../lib/firefox/plugins/
9. ln -s /usr/local/jre1.6.0_27/lib/i386/libnpjp2.so .
10.Edit > Preferences. Under Advanced category > Select Enable Java