This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
I recommend you don't try to do this yourself and use a java library that exists already for this. I've used the one from the site http://www.json.org/ and it would be more than useable in your situation.