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.
you can control number of instance of an object via programming i.e. if you want by writing code in constructor to check the limit before creating any instance e.g. Singleton class which only has one instance. on the other hand Java does not provide any mechanism to control number of instance of any object neither to control garbage collection.