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.
The number of full weeks in a month is four. Do you mean the number of a particular days, like Mondays? For that, I think the GregorianCalendar class would do the trick, with a bit of code on your part of course.