This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
You are attempting to iterate over players.get(i); I don't know what that returns, but your error message indicates it is not iterable. I would have expected it to be a player, and a Player object to have a method that returns a collection of cards (getCards(), getHand(), something like that). Perhaps you need something like players.get(i).getCards().