Java - Why is this code repeating? NoSuchElementException?

Question

I'm learning Java by trying to make a simple Rock-Paper-Scissors game in Eclipse:

package com;


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


public class Game {

    public static void main(String[] args) {
        Game game = new Game();
        game.playerChoice();
        game.aiChoice();
        game.playGame();
    }

public void playGame() {

    if (playerChoice() == "Rock") {
        if (aiChoice() == "Rock") {
                System.out.println("Tie!");
            } else if (aiChoice() == "Paper") {
                System.out.println("AI wins!");
                } else {
                System.out.println("You win!");
                }

        } else if (playerChoice() == "Paper") {
            if (aiChoice() == "Rock") {
                System.out.println("You win!");
            } else if (aiChoice() == "Paper") {
                System.out.println("Tie!");
            } else {
                System.out.println("AI wins!");
            }

        } else {
            if (aiChoice() == "Rock") {
                System.out.println("AI wins!");
            } else if (aiChoice() == "Paper") {
                System.out.println("You win!");
            } else {
                System.out.println("Tie!");
            }
        }
    }

    public String playerChoice() {

        Scanner scanner = new Scanner(System.in);
        String word = null;

        try {
            System.out.println("Type Rock, Paper, or Scissors");
            word = scanner.next();
            System.out.println(word + " is saved as your choice");
        } finally {
            scanner.close();
        }
        return word;
    }

    public String aiChoice() {

        String[] wordlist = {"Rock", "Paper", "Scissors"};
        String word = wordlist [new Random().nextInt(wordlist.length)];
        System.out.println("AI has randomly picked " + word);
        return word;
    }
}

When I input "Rock", "Paper", or "Scissors" in the scanner input I get the following in the console:

Type Rock, Paper, or Scissors
Rock <--- This is what I input into the console
Rock is saved as your choice
AI has randomly picked Scissors
Type Rock, Paper, or Scissors <--- This unintentionally repeats
Exception in thread "main" java.util.NoSuchElementException
    at java.base/java.util.Scanner.throwFor(Unknown Source)
    at java.base/java.util.Scanner.next(Unknown Source)
    at com.Game.playerChoice(Game.java:53)
    at com.Game.playGame(Game.java:17)
    at com.Game.main(Game.java:12)

What am I doing wrong that causes this exception and why does the System.out.println("Type Rock, Paper, or Scissors"); repeat itself? Thank you.

Because you repeatedly call `playerChoice()` and `aiChoice()`. Also, your string comparison is [wrong](https://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java). — shmosel, Jun 13 '18 at 01:38
Read [How do I compare Strings in Java](https://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java) — Erwin Bolwidt, Jun 13 '18 at 01:39

score 0 · Accepted Answer · answered Jun 13 '18 at 01:41

First, do not close the Scanner.. That's causing the NoSuchElement exception

You can move the Scanner to a field variable rather than making a new one for every player choice

public class Game {

    private Scanner sc = new Scanner(System.in);

    public static void main(...

To fix the rest of the problems, there's no purpose in getting choices before the games starts

Just play the game

 public static void main(String[] args) {
    Game game = new Game();
    game.playGame();
}

Then, you need to persist the choices of each player rather than picking again for every method call (causing your input to repeat, and the AI to pick new choices for every comparison)

public void playGame() {
    final String p = playerChoice();
    final String a = aiChoice();

     if (p.equals(a)) {
         if (a.equals("Rock")) {

Please read How do I compare strings in Java?

Java - Why is this code repeating? NoSuchElementException?

1 Answers1