Priyadarshni Gopalakrishnan,
Welcome to JavaRanch.
As you say that you have knowledge of OOPS concepts, so they surely will assist you while learning Java. But, I'll like to tell you that there are considerable differences between Java and C++, so get rid of the C++ cover and give Java a fresh start.
There are a number of good books to begin with Java. "Head First Java by Bert Bates & Kathy Sierra" is a good one.
For SCJP certification Kathy and Bert have written a book as well.
But, my suggestion is that instead of rushing into certification first
you should work hard to enrich your knowledge of Java.
Wish you luck..!!