Java：创建一个空接口以从一个属性访问不同的类？

Question

I'm creating a FreeCell game, and at the end of the game I want it to print out the users moves. So the solution is a Move[]. The Move class looks like:

public class Move
{

   private Card card;
   private Location source;
   private Location target;

   public Move(Card card, Location source, Location target)
   {
      this.card = card;
      this.source = source;
      this.target = target;
   }
}

I want Location to be able to store the three different types of locations in a FreeCell game: The Cells (which can hold 1 card), the Cascades (which is where the cards are dealt), and the Foundations (where the cards are placed to solve the game). So I need Location to be able to store objects of the Cell, Cascade, and Foundation classes. But these classes don't all have any attributes or methods that are shared between them, so a parent class doesn't make much sense. Furthermore, Cascade already extends LinkedList to avoid warnings when creating an array of LinkedLists, and it can't extend two parent classes.

So is there an elegant solution to this? Should I create a blank interface called Location, or is there an easier aspect of OOP that I'm not thinking of that can be used here?

Answer 1

Your Location s are just a small fixed set of values right:
Cells 1 to 4
Foundation 1 to 4
Cascade 1 to 8

You could use enum s.

public interface Location {}

public enum Cell implements Location { ONE, TWO, THREE, FOUR }