Rock-paper-scissors app in Java

This is the first post. I created a rock-paper-scissors app that is written in various ways.

Creation period: 2 days Language: Java Environment: MacOS, Terminal Text editor: Atom

It is a game operated by commands. The rules are as follows.

――Three games --Janken's hands are managed by an array --The CPU creates a random number and decides the hand --The player decides his hand by changing the entered characters into numerical values. ――Judging victory or defeat by numerical value --Finally, display the result of the game

The actual screen looks like this.

スクリーンショット 2018-08-23 2.15.35.png

Janken class

It is a battle class.

package jankenapp;

public class Janken {
  static String[] handList = {"Goo","Choki","Par"};

  static void startMessage() {
    System.out.println("Let's play rock-paper-scissors! It ’s three games!");

  static void endMessage() {
    System.out.println("Thank you very much! Let's play again!");

  public static void main(String[] args) {
    Player player = new Player();
    CPU cpu = new CPU();
    Judge judge = new Judge();

    //Opening greeting

    for (int i = 1; i <= 3; i++) {
     System.out.println("【" + i + "Round]");

     //CPU randomly creates hands
     //Player inputs hand
     // Player,Show CPU hand
     System.out.println("・ Your hand:" + handList[player.getHand()]);
     System.out.println("・ My hand:" + handList[cpu.getHand()]);
     judge.judgement(cpu.getHand(), player.getHand());
    } //End of repetition
    //View results
    //Closing remarks

Player class

I use Scanner to get the hand as a string and digitize it with a switch statement.

package jankenapp;
import java.util.*;

public class Player {
  int hand;

  public void setHand() {
    System.out.print("Please enter one of "Goo", "Choki", and "Par". >");
    Scanner sc = new Scanner(;
    String inputHand = sc.nextLine();

    switch(inputHand) {
      case "Goo":
        hand = 0;
      case "Choki":
        hand = 1;
      case "Par":
        hand = 2;
        System.out.println("I made a mistake, so I'm done ...");

  public int getHand() {
    return hand;

CPU class

The hand is decided randomly by the random method.

package jankenapp;
import java.util.*;

public class CPU {
    int hand;

    public void setHand() {
     double rand = Math.random() * 3;
     hand = (int)rand;

    public int getHand() {
      return this.hand;

Judge class

It is a class of the judgment of victory or defeat and the result of the game. The judgment method is to quantify each hand and calculate it by (CPU hand-player's hand +3)% 3. The number of wins, losses and draws of the player is counted, and the result is displayed in an if statement.

Package jankenapp;

public class Judge {
  int judge;
  int win;
  int lose;
  int even;

  public void judgement(int cpuHand, int playerHand) {
    judge = (cpuHand - playerHand + 3 ) % 3;

    switch(judge) {
      case 0:
        System.out.println("This is Aiko!");
      case 1:
        System.out.println("You win!");
      case 2:
        System.out.println("You lose!");

  public void result() {
    System.out.println("[Result of victory or defeat]");
    System.out.println("win:" + win + "Times");
    System.out.println("Losing:" + lose + "Times");
    System.out.println("Aiko:" + even + "Times");
    if (win > lose) {
      System.out.println("This game is yours! Congrats!");
    } else if (win < lose) {
      System.out.println("This game is your loss! Do not mind!");
    } else {
      System.out.println("This game is a draw!");

I'm self-taught, so I'm sorry if there are any unsightly parts. I would be grateful if you could give me any advice.

Thank you for browsing to the end.

【reference】 A little application of the rock-paper-scissors algorithm (I referred to the judgment formula.)

Postscript (8/23) I noticed that even if I make a mistake in the input, the default value will give a goo. I will take measures.

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