Originally posted by ramya ramya: ...is it a good practice to start with JLS...
In my opinion, no. The JLS is a good reference for tricky situations, but overall it's at a level more complex than you will need for the SCJP exam. I'm not convinced that working through the JLS would be time well spent for most people.
Instead, I recommend starting with a good introductory Java book, then moving to a good SCJP preparation book. Along the way, write lots of test code, use the API and JLS for reference, and as you get closer to the exam, take lots of mock exams.