This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
You can't. A typecast of an object reference cannot change the object into a different kind of object.
If you had an object reference that was declared as a java.util.Date, but you knew that it actually referred to one of the subclasses, java.sql.Date or java.sql.Timestamp, you could typecast the object reference to one of those subclasses.