109 lines
2.1 KiB
Java
109 lines
2.1 KiB
Java
//: patterns/PaperScissorsRock.java
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// Demonstration of multiple dispatching.
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import java.util.*;
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enum Outcome { WIN, LOSE, DRAW }
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interface Item {
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Outcome compete(Item it);
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Outcome eval(Paper p);
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Outcome eval(Scissors s);
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Outcome eval(Rock r);
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}
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class Paper implements Item {
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@Override
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public Outcome compete(Item it) {
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return it.eval(this);
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}
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@Override
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public Outcome eval(Paper p) {
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return Outcome.DRAW;
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}
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@Override
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public Outcome eval(Scissors s) {
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return Outcome.WIN;
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}
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@Override
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public Outcome eval(Rock r) {
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return Outcome.LOSE;
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}
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@Override
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public String toString() { return "Paper"; }
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}
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class Scissors implements Item {
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@Override
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public Outcome compete(Item it) {
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return it.eval(this);
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}
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@Override
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public Outcome eval(Paper p) {
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return Outcome.LOSE;
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}
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@Override
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public Outcome eval(Scissors s) {
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return Outcome.DRAW;
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}
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@Override
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public Outcome eval(Rock r) {
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return Outcome.WIN;
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}
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@Override
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public String toString() { return "Scissors"; }
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}
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class Rock implements Item {
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@Override
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public Outcome compete(Item it) {
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return it.eval(this);
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}
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@Override
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public Outcome eval(Paper p) {
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return Outcome.WIN;
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}
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@Override
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public Outcome eval(Scissors s) {
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return Outcome.LOSE;
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}
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@Override
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public Outcome eval(Rock r) {
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return Outcome.DRAW;
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}
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@Override
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public String toString() { return "Rock"; }
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}
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class ItemFactory {
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public static Item newItem() {
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switch((int)(Math.random() * 3)) {
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default:
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case 0:
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return new Scissors();
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case 1:
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return new Paper();
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case 2:
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return new Rock();
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}
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}
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}
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class Compete {
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public static Outcome match(Item a, Item b) {
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System.out.print(a + " <--> " + b + " : ");
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return a.compete(b);
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}
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}
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public class PaperScissorsRock {
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public static void main(String args[]) {
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ArrayList<Item> items = new ArrayList<>();
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for(int i = 0; i < 40; i++)
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items.add(ItemFactory.newItem());
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for(int i = 0; i < items.size()/2; i++)
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System.out.println(
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Compete.match(
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items.get(i), items.get(i*2)));
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}
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} ///:~
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