Note:If you have RPM on your Linux box, you should first find out if Java is already installed using RPM. If Java is not installed using RPM, you should skip reading.
Open Terminal Window
Login as the super user
Try to find jre package by typing: rpm -qa
If RPM reports a package similar to jre--fcs, then Java is installed with RPM.
Note:Normally, you do not need to uninstall Java with RPM, because RPM is able to uninstall the old version of Java when installing a new version! You may skip reading, unless you want to remove Java permanently.