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Thread: Trying to compare an int variable to an index in an array

  1. #1
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    Default Trying to compare an int variable to an index in an array

    I have a method that is called that returns the value of 2 dice rolls, one for the computer and one for the player.

    I have an array that has all the possible values of dice rolls.

    I want to compare the values of the rolls to the values in the array and then declare the winner by whoever has the lowest array index value. This where the problem occurs. I tried to compare the value of the score to the array this way ::::: scoreOrder[playerScore] < scoreOrder[compScore] ::::: but this doesn't work.

    The error I receive is: Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: and then the value of the score.

    All the comparative logic in my If statement needs to be corrected.



    This is what I have so far:

    import java.util.*;
     
    public class Program08 
    {
    	public static void main(String[] args)
    	{
    		Scanner stdIn = new Scanner(System.in);
     
    		//variables
     
    		int playerScore = 1;
    		int compScore = 1;
     
    		playerScore = diceRoll(playerScore);
    		compScore = diceRoll(compScore);
     
    		int scoreOrder[] = {21,66,55,44,33,22,11,65,64,63,62,61,54,53,52,51,43,42,41,32,31};
     
    		if (scoreOrder[playerScore] > scoreOrder[compScore])
    		{
    			System.out.println("player wins");
    		}
    		else if (scoreOrder[playerScore] < scoreOrder[compScore])
    		{
    			System.out.println("computer wins");
    		}
    		else
    		{
    			System.out.println("tie");
    		}
     
     
    	}
     
    	public static int diceRoll(int x)
    	{
    		double die1 = (int) (Math.random()*6+1);
    		double die2 = (int) (Math.random()*6+1);
    		System.out.println(die1);
    		System.out.println(die2);
    		x = (int) Math.max(die1, die2)*10 + (int) Math.min(die1, die2);
    		System.out.println("roll is: " + x);
    		return x;
     
    	}
    }


  2. #2
    Super Moderator curmudgeon's Avatar
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    Default Re: Trying to compare an int variable to an index in an array

    This statement: scoreOrder[playerScore], doesn't make sense. The score can not be the index of your array since it varies from 11 to 66, and your array does not contain over 60 items. I think that instead you want to find the index of the score in the array, and for that you'll need a for loop.

    Oh, next time you have a similar error, you'll want to show us with a comment which line is causing the error or exception.

  3. The Following User Says Thank You to curmudgeon For This Useful Post:

    TCDave (November 18th, 2012)

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    Default Re: Trying to compare an int variable to an index in an array

    Sorry about that. Here is the full error message:

    Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 61
    at Program08.main(Program08.java:19)

    Thanks for the advise. It took a bit of thinking to see what direction you were pointing me towards. Making a for loop and then comparing everything in an if statement solved the problem. Thanks.
    Last edited by TCDave; November 18th, 2012 at 02:30 AM. Reason: grammar

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    curmudgeon (November 18th, 2012)

  6. #4
    Super Moderator curmudgeon's Avatar
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    Default Re: Trying to compare an int variable to an index in an array

    You're welcome. Glad you've figured it out, and glad that you really did it on your own. Good show!

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