// enums/RoShamBo1.java // (c)2016 MindView LLC: see Copyright.txt // We make no guarantees that this code is fit for any purpose. // Visit http://OnJava8.com for more book information. // Demonstration of multiple dispatching // {java enums.RoShamBo1} package enums; import java.util.*; import static enums.Outcome.*; interface Item { Outcome compete(Item it); Outcome eval(Paper p); Outcome eval(Scissors s); Outcome eval(Rock r); } class Paper implements Item { @Override public Outcome compete(Item it) { return it.eval(this); } @Override public Outcome eval(Paper p) { return DRAW; } @Override public Outcome eval(Scissors s) { return WIN; } @Override public Outcome eval(Rock r) { return LOSE; } @Override public String toString() { return "Paper"; } } class Scissors implements Item { @Override public Outcome compete(Item it) { return it.eval(this); } @Override public Outcome eval(Paper p) { return LOSE; } @Override public Outcome eval(Scissors s) { return DRAW; } @Override public Outcome eval(Rock r) { return WIN; } @Override public String toString() { return "Scissors"; } } class Rock implements Item { @Override public Outcome compete(Item it) { return it.eval(this); } @Override public Outcome eval(Paper p) { return WIN; } @Override public Outcome eval(Scissors s) { return LOSE; } @Override public Outcome eval(Rock r) { return DRAW; } @Override public String toString() { return "Rock"; } } public class RoShamBo1 { static final int SIZE = 20; private static SplittableRandom rand = new SplittableRandom(47); public static Item newItem() { switch(rand.nextInt(3)) { default: case 0: return new Scissors(); case 1: return new Paper(); case 2: return new Rock(); } } public static void match(Item a, Item b) { System.out.println( a + " vs. " + b + ": " + a.compete(b)); } public static void main(String[] args) { for(int i = 0; i < SIZE; i++) match(newItem(), newItem()); } } /* Output: Scissors vs. Rock: LOSE Scissors vs. Paper: WIN Rock vs. Paper: LOSE Rock vs. Rock: DRAW Rock vs. Paper: LOSE Paper vs. Scissors: LOSE Rock vs. Paper: LOSE Scissors vs. Scissors: DRAW Scissors vs. Rock: LOSE Scissors vs. Paper: WIN Scissors vs. Rock: LOSE Paper vs. Scissors: LOSE Rock vs. Rock: DRAW Scissors vs. Scissors: DRAW Paper vs. Paper: DRAW Scissors vs. Paper: WIN Scissors vs. Rock: LOSE Scissors vs. Paper: WIN Rock vs. Paper: LOSE Rock vs. Scissors: WIN */