I dont understand why I am getting ArrayIndexOutOfBoundsException?

Question

I keep getting ArrayIndexOutOfBoundsException. I tried to resize all the arrays and traced my code but nothing seems to pop up to me!

I am comparing the numbers between arr and brr. I am trying to print out the numbers that are in brr but not arr and the numbers that are repeated less often than in brr.

I am putting these numbers in sperate array and printing it out. I also tried to do it using Lists but im getting the same Exception.

public class Solution {

static int[] array = new int[200];
static int nextIndex = 0;


public static void main(String[] args) {

    Scanner s = new Scanner(System.in);


    System.out.println("enter n: ");
    int n = s.nextInt();
    System.out.println("enter numbers in arr: ");
    //List<Integer> arr = new ArrayList<>();
    int arr[];
    arr = new int[200];

    for (int i=0; i<n ; i++){

        arr[i] = s.nextInt();
    }



    System.out.println("enter m: ");
    int m = s.nextInt();
    //List<Integer> brr = new ArrayList<>();
    int brr[];
    brr = new int[200];
    System.out.println("enter numbers in brr: ");
    for (int i=0; i<m ; i++){

        brr[i] = s.nextInt();
    }




    //System.out.println("The missing nums are : ");
    //List<Integer> finalArray;
    //ArrayList<Integer> finalArray;

    int finalArray[];
    finalArray = new int[200];

    finalArray = missingNums(arr,brr);

    for (int i =0; i<finalArray.length; i++){
        System.out.println(finalArray[i]);
    }

}

public static int[] missingNums(int arr[], int brr[]){

    int oFreq = 1, fFreq = 0;

    int num, num2=-1;

    for (int i=0; i<brr.length; i++){
        num = brr[i];
        //finding the frequency for each num in brr at a time
        for (int j=0; j< brr.length; j++)
            if (brr[j + 1] == num) {
                oFreq++;
                //System.out.println(oFreq);
            }
        //checking if the same num exists in arr and storing it in num2
        for (int x = 0; x<arr.length; x++){
            if (arr[x] == num)
                num2 = arr[x];
            else
                push(num);
                //nums.add(num);


        }
        //if the same number as in brr exists in arr find its frequency in arr
        if (num2 != -1){
            //find frequency of the number in arr
            for (int x = 0; x<arr.length; x++){
                if (num2 == arr[x])
                    fFreq++;
            }
        }
        if (oFreq > fFreq)
            push(num);

    }

    return (array);

}


public static void push(int e) {
    array[nextIndex] = e;
    ++nextIndex;
}

public static int pop() {
    --nextIndex;
    return array[nextIndex];
}
}

When iterating `j`from `0` to strictly less than`brr.length`, the last value of j will be corresponding to the last element of the array. `j+1` will then correspond to the element that comes after the last element in the array, which will be out of bounds. — JohEker, Jan 31 '19 at 20:01
Try stepping through the code line by line. Also, what if `n` or `m` is greater than 200? — Andrew S, Jan 31 '19 at 20:02
@MahmoudHamra not the same error: if you use `j+1` the ArrayIndexOutOfBoundsException will happen on the line with `brr[j + 1]`. If you replace it with `j` then the ArrayIndexOutOfBoundsException will happen in the `push` method (which the exception stacktrace would have told you). You can forego the exception in `push` by sizing the static `array` appropriately: `static int[] array = new int[40000];` — Thomas Kläger, Feb 01 '19 at 06:15

score 0 · Answer 1 · answered Jan 31 '19 at 20:36

0

The issue is that you are iterating through the array brr as often as the user inputs. This means you are assuming the input is <= 200. You need to set the size of these arrays to the inputs n and m. Hope this helps!

answered Jan 31 '19 at 20:36

J. Lengel

570
3
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I dont understand why I am getting ArrayIndexOutOfBoundsException?

1 Answers1