Hi Kalyan,
Welcome to JavaRanch!
You seem to be getting a bit of a hard time from the various bartenders and sheriffs round here so, assuming that you're now fully conversant with the rules for naming, which forum is appropriate for your query and not to post multiply, I'm going to throw you a bone.
We're really a friendly bunch here at JavaRanch. Take a look at this
Being a Descendant of Object page of Sun's Java Language Tutorial. Hopefully that should improve your understanding.
The simple answer to your question is that classes that can be cloned (i.e. have a functional clone() method) must implement the Cloneable interface. Object does not but its descendants can, if they choose, as they inherit the protected clone() method. Not a great explanation, but it might help.
Jules