Rock-paper-scissors

Core exercise

Paper beats rock, rock beats scissors, scissors beats paper. The choices are coded as integers: 1 = rock (pierre), 2 = paper (papier), 3 = scissors (ciseaux).

Goals: Constants, switch, randomness, game loop.

Features

• nomDuChoix(int choix) returns "pierre", "papier" or "ciseaux".
• determinerVainqueur(int utilisateur, int ordinateur) returns 1 (user), -1 (computer) or 0 (draw).
• A game loop that plays again as long as the user wishes.

Steps

1. Represent the choices by integers (1, 2, 3).
2. lireChoixUtilisateur(Scanner sc) → an integer between 1 and 3, validation included.
3. tirerChoixOrdinateur() with Random.
4. determinerVainqueur(u, o) → the rule of the game, isolated.
5. The loop: play a round, print the result, offer to play again.

Criteria: Robust input, correct winning logic, readable code.

A workshop goes here: you write and run code in it. It requires JavaScript.

Starting code

Jeu.java

import java.util.Random;
import java.util.Scanner;

public class Jeu {

    public static String nomDuChoix(int choix) {
        // TODO : 1 = pierre, 2 = papier, 3 = ciseaux
        return "";
    }

    public static int tirerChoixOrdinateur() {
        // TODO : un entier entre 1 et 3
        return 1;
    }

    public static int lireChoixUtilisateur(Scanner sc) {
        // TODO : lire un entier entre 1 et 3, en redemandant si besoin
        return 1;
    }

    public static int determinerVainqueur(int utilisateur, int ordinateur) {
        // TODO : 1 = l'utilisateur gagne, -1 = l'ordinateur gagne, 0 = egalite
        return 0;
    }
}

Exercices.java

import java.util.Scanner;

public class Exercices {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int utilisateur = Jeu.lireChoixUtilisateur(sc);
        int ordinateur = Jeu.tirerChoixOrdinateur();
        System.out.println("Vous : " + Jeu.nomDuChoix(utilisateur));
        System.out.println("Ordi : " + Jeu.nomDuChoix(ordinateur));
        System.out.println("Resultat : " + Jeu.determinerVainqueur(utilisateur, ordinateur));
        sc.close();
    }
}

The core exercise is validated in the workshop, which requires JavaScript.

Hint 1

Arithmetic trick: with 1, 2, 3, the user wins exactly when (u - o + 3) % 3 == 1. If that looks obscure, write out the nine cases by hand first; the checks test them all.

Extensions

• Cumulative score (first to 3 wins).
• The “rock-paper-scissors-lizard-Spock” variant.