Hi Ananth,
You can find a good free stuff at
http://java.sun.com/docs/books/tutorial/information/download.html.
I also recommend the book "Thinking in
Java 3rd Edition" which is available for free download at author's web site :
http://www.pythoncriticalmass.com/downloads/TIJ-3rd-edition4.0.zip Both stuff are not focused on certification exam, but it's a good start point and should be used as reference.
If you want a well focused on certification exam stuff, I suggest you to buy K&B book. I think it's the most used and most complete book aiming certification.
I treasure each cent I paid for it. For sure you won't regret.
"If someone asks you to do something you don't know how to, don't tell I don't know, tell I can learn instead." - Myself