Java while-loop stops after one iteration

Question

I'm trying to create a rock, paper, scissors, lizard, spock program that repeats itself until the user chooses to exit. However, I can't figure out quite how to make the program loop. It keeps exiting after one game. I think it might have to do with how my while statement is set up, But I'm not entirely sure what to do to fix it. Thanks.

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

public class project2_rpsls {

public static void main(String[] args) 
{
    int round=0;
    String uMove = null, cMove = null/*, loop*/;
    Scanner scan=new Scanner(System.in);
    /*System.out.println("Would you like to play?");
    loop=scan.next();
    loop=loop.toUpperCase();
    while (loop.equals("Y"))*/

        while (round>=0) 
        {
            round++;
        }
        //get the moves
        {
        uMove = getuMove();
        cMove = getcMove();
        }
        //Determining the winner
        {
            String winner;
                if (cMove.equals(uMove))
                        {
                        winner="It was a tie!";
                        }
                else if (uMove.equals("ROCK") && cMove.equals("LIZARD") ||
                        uMove.equals ("ROCK") && cMove.equals("SCISSORS"))
                        {
                        winner="You Win!";
                        }
                else if (uMove.equals("PAPER") && cMove.equals("ROCK") ||
                        uMove.equals ("PAPER") && cMove.equals("SPOCK"))
                        {
                        winner="You Win!";
                        }
                else if (uMove.equals("SCISSORS") && cMove.equals("PAPER") ||
                         uMove.equals ("SCISSORS") && cMove.equals("LIZARD"))
                        {
                        winner="You Win!";
                        }
                else if (uMove.equals("LIZARD") && cMove.equals("SPOCK") ||
                         uMove.equals ("LIZARD") && cMove.equals("PAPER"))
                        {
                        winner="You Win!";
                        }
                else if (uMove.equals("SPOCK") && cMove.equals("SCISSORS") ||
                         uMove.equals ("SPOCK") && cMove.equals("ROCK"))
                        {
                        winner="You Win!";
                        }
                else 
                        {
                        winner="You Lose!";
                        }
            System.out.println("The computer picked " + cMove + " -- " + winner);
            }

            scan.close();
}


//Get user's move
private static String getuMove() 

{
Scanner scan=new Scanner(System.in);
    String uMove="test";
    while (!uMove.equals("ROCK") &&
            !uMove.equals ("PAPER")&&
            !uMove.equals("SCISSORS")&&
            !uMove.equals("LIZARD")&&
            !uMove.equals("SPOCK"))
    {
        System.out.println("Please enter your move: ");
        uMove=scan.next();
        uMove=uMove.toUpperCase();  
    }
    scan.close();
    return uMove;

    }

//Get computer's move
private static String getcMove() {
String cMove;
Random cMoveInt = new Random();
int rnum;
rnum=cMoveInt.nextInt(5);

    {
        if (rnum == 1) {
            cMove = "ROCK";
        }
        else if (rnum == 2) {
            cMove = "PAPER";
        }
        else if (rnum == 3){
            cMove = "SCISSORS";
        }
        else if (rnum == 4){
            cMove = "LIZARD";
        }
        else {
            cMove = "SPOCK";
        }

    }

        return cMove;
}

}

Thanks for the pointers. After I changed my while loop to

        while (round>=0) 
        {
            round++;

        //get the moves
        uMove = getuMove();
        cMove = getcMove();

        //Determining the winner
        {
            String winner;
             ...etc.

I got the following error.

   Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at project2_rpsls.getuMove(project2_rpsls.java:82)
at project2_rpsls.main(project2_rpsls.java:22)

From my research, it seems as though my scanner isn't finding anything to read, but I don't see how, because it's supposed to be reading user input.

May you want to fix the sample code? Taking into account comments, it will get trapped in an infinite loop... — dunadar
– dunadar, Commented Oct 22, 2012 at 20:43
Learn about enumerations: docs.oracle.com/javase/tutorial/java/javaOO/enum.html — Dave Jarvis
– Dave Jarvis, Commented Oct 22, 2012 at 20:45
To the downvoters: why is this not a good question? A novice programmer has a problem, has stated the problem, and shown the code. This is a better question than the countless others that show no code. — Dave Jarvis
– Dave Jarvis, Commented Oct 22, 2012 at 20:47

Dave Jarvis · Accepted Answer · 2012-10-22 21:09:13Z

7

Your

while (round >= 0)
{
    round++;
}

...does nothing but increment the round variable until it wraps around back to zero (after roughly 4 billion loops). Then the rest of your code runs. Move the rest of the code into the loop.

For example:

while (round >= 0)
{
    round++;

    uMove = getuMove();
    cMove = getcMove();

    String winner;

    // ...etc.
}

Also note that the following braces are redundant:

   {
     uMove = getuMove();
     cMove = getcMove();
   }

This can be written as:

   uMove = getuMove();
   cMove = getcMove();

edited Oct 22, 2012 at 21:09

Dave Jarvis

31.3k43 gold badges186 silver badges326 bronze badges

answered Oct 22, 2012 at 20:44

T.J. Crowder

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