OnJava8-Examples/enums/RoShamBo5.java

// enums/RoShamBo5.java
// (c)2020 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.
// Multiple dispatching using an EnumMap of EnumMaps
// {java enums.RoShamBo5}
package enums;
import java.util.*;
import static enums.Outcome.*;

enum RoShamBo5 implements Competitor<RoShamBo5> {
  PAPER, SCISSORS, ROCK;
  static EnumMap<RoShamBo5,EnumMap<RoShamBo5,Outcome>>
    table = new EnumMap<>(RoShamBo5.class);
  static {
    for(RoShamBo5 it : RoShamBo5.values())
      table.put(it, new EnumMap<>(RoShamBo5.class));
    initRow(PAPER, DRAW, LOSE, WIN);
    initRow(SCISSORS, WIN, DRAW, LOSE);
    initRow(ROCK, LOSE, WIN, DRAW);
  }
  static void initRow(RoShamBo5 it,
    Outcome vPAPER, Outcome vSCISSORS, Outcome vROCK) {
    EnumMap<RoShamBo5,Outcome> row =
      RoShamBo5.table.get(it);
    row.put(RoShamBo5.PAPER, vPAPER);
    row.put(RoShamBo5.SCISSORS, vSCISSORS);
    row.put(RoShamBo5.ROCK, vROCK);
  }
  @Override
  public Outcome compete(RoShamBo5 it) {
    return table.get(this).get(it);
  }
  public static void main(String[] args) {
    RoShamBo.play(RoShamBo5.class, 20);
  }
}
/* Output:
ROCK vs. ROCK: DRAW
SCISSORS vs. ROCK: LOSE
SCISSORS vs. ROCK: LOSE
SCISSORS vs. ROCK: LOSE
PAPER vs. SCISSORS: LOSE
PAPER vs. PAPER: DRAW
PAPER vs. SCISSORS: LOSE
ROCK vs. SCISSORS: WIN
SCISSORS vs. SCISSORS: DRAW
ROCK vs. SCISSORS: WIN
SCISSORS vs. PAPER: WIN
SCISSORS vs. PAPER: WIN
ROCK vs. PAPER: LOSE
ROCK vs. SCISSORS: WIN
SCISSORS vs. ROCK: LOSE
PAPER vs. SCISSORS: LOSE
SCISSORS vs. PAPER: WIN
SCISSORS vs. PAPER: WIN
SCISSORS vs. PAPER: WIN
SCISSORS vs. PAPER: WIN
*/