What OO design patterns can be used in Texas holdem poker

I need to write a little Texas holdem poker program using Java. I am asked to put some fancy design patterns in the program for education purpose. Cards are given to players by some API so I only need to write a cards comparison logic to judge who wins the game. Well, the logic is not too hard and I have got the core algorithm done. Now im wondering what OO design patterns can be used?

any thought is welcome. Thanks