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1. Overview

In this short tutorial, we'll see how to create a simple “Rock-Paper-Scissors” game in Java.

2. Create Our “Rock-Paper-Scissors” Game

Our game will allow players to enter “rock”, “paper”, or “scissors” as the value of each move.

First, let's create an enum for the moves:

enum Move {
    ROCK("rock"),
    PAPER("paper"),
    SCISSORS("scissors");

    private String value;
    
    //...
}

Then, let's create a method that generates random integers and returns the computer's move:

private static String getComputerMove() {
    Random random = new Random();
    int randomNumber = random.nextInt(3);
    String computerMove = Move.values()[randomNumber].getValue();
    System.out.println("Computer move: " + computerMove);
    return computerMove;
}

And a method that checks if the player wins:

private static boolean isPlayerWin(String playerMove, String computerMove) {
    return playerMove.equals(Move.ROCK.value) && computerMove.equals(Move.SCISSORS.value)
            || (playerMove.equals(Move.SCISSORS.value) && computerMove.equals(Move.PAPER.value))
            || (playerMove.equals(Move.PAPER.value) && computerMove.equals(Move.ROCK.value));
}

Finally, we'll use them to form a complete program:

Scanner scanner = new Scanner(System.in);
int wins = 0;
int losses = 0;

System.out.println("Welcome to Rock-Paper-Scissors! Please enter \"rock\", \"paper\", \"scissors\", or \"quit\" to exit.");

while (true) {
    System.out.println("-------------------------");
    System.out.print("Enter your move: ");
    String playerMove = scanner.nextLine();

    if (playerMove.equals("quit")) {
        System.out.println("You won " + wins + " times and lost " + losses + " times.");
        System.out.println("Thanks for playing! See you again.");
        break;
    }

    if (Arrays.stream(Move.values()).noneMatch(x -> x.getValue().equals(playerMove))) {
        System.out.println("Your move isn't valid!");
        continue;
    }

    String computerMove = getComputerMove();

    if (playerMove.equals(computerMove)) {
        System.out.println("It's a tie!");
    } else if (isPlayerWin(playerMove, computerMove)) {
        System.out.println("You won!");
        wins++;
    } else {
        System.out.println("You lost!");
        losses++;
    }
}

As can be seen above, we use Java Scanner to read the user input value.

Let's play a bit and see the output:

Welcome to Rock-Paper-Scissors! Please enter "rock", "paper", "scissors", or "quit" to exit.
-------------------------
Enter your move: rock
Computer move: scissors
You won!
-------------------------
Enter your move: paper
Computer move: paper
It's a tie!
-------------------------
Enter your move: quit
You won 1 times and lost 0 times.
Thanks for playing! See you again.

3. Conclusion

In this quick tutorial, we've learned how to create a simple “Rock-Paper-Scissors” game in Java.

As always, the example code from this article can be found over on GitHub.

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