Many thanks Leelavati for your response.
chariflakchiri , I think you interpreted in a different way.Can you visit
http://www.objectdiscovery.com/programming/java/ooad/outline.html.
Then you will come to know what is required for you to say that you know OOAD. See what percentage of the tutorial you really need to get SCJP, SCWCD, SCBCD.