Getting an Array error message

Question

I'm just starting java programing and I've been doing really good so far. So the program I am having problems with works just after it goes through there is an error message, yet the program worked as I wanted it to. The program in question is supposed to role a die 1000 times and count how many times each side of the die was rolled out of 1000. its supposed to display this, which it does.

Here is my program: and the error message I put below it. Thanks for any help in advanced!

public class Test
{
     public static void main(String[] args)
     {//create array of 1,000 random numbers
         int[] randomNumbers = new int[1000];

         for(int i = 0; i < randomNumbers.length; i++)
             randomNumbers[i] =1 +(int)(Math.random() * 6);
         { //initialize count
             int[] counts = countInts(randomNumbers);
             displayIntCount(counts);
         }
     }

     public static int[] countInts(int[] ints)
     { //creat new array to hold occurence values
         int[] counts = new int[6];
         for(int i = 1; i <=counts.length; i++)
             for(int j=0;j<ints.length;j++)
                 if(ints[j] == i)
                     counts[i-1]++;  
         return counts;
     }

     public static void displayIntCount(int[] counts)
     {//display the occurrences
         for (int i = 0; i < counts.length; i++)
                 System.out.println("The number 1 occurs "+counts[i]+" times \nThe number 2 occurs "+counts[i+1]+" times \nThe number 3 occurs "+counts[i + 2]+ " times \nThe number 4 occurs " +counts[i+3]+ " times \nThe number 5 occurs " +counts[i + 4]+ " times \nThe number 6 occurs "+counts[i + 5]+ " times");
     }
}

Don't forget the error message.

Sotirios Delimanolis
– Sotirios Delimanolis

2014-03-09 22:43:57 +00:00
Commented Mar 9, 2014 at 22:43 — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Mar 9, 2014 at 22:43
What does the error say?

SLaks
– SLaks

2014-03-09 22:44:34 +00:00
Commented Mar 9, 2014 at 22:44 — SLaks
– SLaks, Commented Mar 9, 2014 at 22:44

Sharif Mamun · Accepted Answer · 2014-03-09 22:55:35Z

2

You are making mistake in displayIntCount(), I made the change for you:

public class Test
{
     public static void main(String[] args)
     {//create array of 1,000 random numbers
      int[] randomNumbers = new int[1000];

      for(int i = 0; i < randomNumbers.length; i++)
      randomNumbers[i] =1 +(int)(Math.random() * 6);
      { //initialize count
       int[] counts = countInts(randomNumbers);
       displayIntCount(counts);
      }
     }

    public static int[] countInts(int[] ints)
        { //creat new array to hold occurence values
         int[] counts = new int[6];
         for(int i = 1; i <=counts.length; i++)
             for(int j=0;j<ints.length;j++)
                 if(ints[j] == i)
                     counts[i-1]++;  
         return counts;
        }

     public static void displayIntCount(int[] counts)
      {//display the occurrences
         for (int i = 0; i < counts.length; i++)
             System.out.println("The number "+ (i+1) +" occurs "+counts[i]+ " times");
    } 
}

You have only 6 elements in the array and after running 6 times, you are running out of index!

edited Mar 9, 2014 at 22:55

answered Mar 9, 2014 at 22:50

Sharif Mamun

3,6046 gold badges36 silver badges52 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

imtheman Over a year ago

Probably should be "The number "+(i+1) in displayIntCount()

user3399714 Over a year ago

Thank you very much! I tried to upvote you but I need a reputation of like 15 I guess. but when I get there I will upvote you!

Michael Berry · Accepted Answer · 2014-03-09 22:47:00Z

1

For clarification, the exception is:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 6 at Test.displayIntCount(Test.java:38) at Test.main(Test.java:20) Java Result: 1

The problem is in displayIntCount(), you're looping through with i up until the last index in the array - but then trying to access i+1 through to i+5.

You probably want to therefore change the condition to counts.length-5. In this case it seems like the program just works because the exception causes it to bow out and fail to print anything (and since this was a case you shouldn't have hit so didn't want to print anything anyway, the normal output stays ok.)

answered Mar 9, 2014 at 22:47

Michael Berry

72.8k23 gold badges165 silver badges227 bronze badges

Collectives™ on Stack Overflow

Getting an Array error message

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related