Satish, Thinking In Java has exercises at the end of each chapter. You could also check a university website. Many professors put their homework assignments online. NYU and many others have solutions and answers available.
UMASS has got some interesting graduate level courses online,they are pretty good and the best part is they are for free. They might prompt for a user name when you enter the course, you can just type in anything as user name and you are good to go.