please kindly assist me in adding sun Java in my repository or ppa

Which version of Ubuntu ?

If your running the newest version use these commands in the terminal:

sudo add-apt-repository ppa:ferramroberto/java
sudo apt-get update
sudo apt-get install sun-java6-jre sun-java6-plugin

Sun Java is now available for info and downloads from the Oracle website which is now the outlet for all such Sun products - http://www.oracle.com ........

When you find the technical assistance section for Java, and downloads, you will find installation instructions given, but be sure to select the right package, because Windows versions are also given alongside of the 64 bit Unix.

Do you want the JRE package - Java runtime, which enables applets on webpages, some chat programs, etc.... ...or, do you want the JDK - Development kit, which is used for making professional level programs (or a mess-up!?!??).

If, once you have installed it and still nothing seems to work, you could go back and try the "Iced Tea" Ubuntu package which should work perfectly well and install with Firefox and Ubuntu OK.
Check in the Firefox browser that Java plugin is enabled OK.

New to Ubuntu:
- read the Ubuntu Manual, it's very informative: http://ubuntu-manual.org/
Click on the "download Button" to download the latest PDF version.

The Ubuntu 11.04 Unity interface
http://theravingrick.blogspot.com/2011/04/my-effort-at-writing-help-for-unity.html
The Unity interface: http://www.omgubuntu.co.uk/natty/#what

- https://help.ubuntu.com/community/SwitchingToUbuntu/FromWindows
- The Ubuntu pocket guide: http://www.ubuntupocketguide.com/
- The online help https://help.ubuntu.com/10.10/index.html

contrary to what martin j. marsh said about icedtea running perfectly, i find that many java apps from websites don't work properly, if they run at all. you might have to test both on your machine to see which runs better.

icedtea is available in the software center.