The Java Runtime Environment (JRE) is required if you need to run any java-based applications on your Ubuntu machine. Many times this is required for certain websites and is always a good addition to your installed package base. To install the Java Runtime Environment including the plugin for Mozilla Firefox simply run the following command. (note: you will need to have additional repositories enabled. See How to add extra repositories.
sudo aptitude install sun-java6-jre sun-java6-plugin sun-java6-bin
You will have to agree to the DLJ license terms to install this package. To find out more about the terms of the DLJ visit the DLJ FAQ.
Works!! Thanks.