How array has been accessed with an illegal index

Question

I am new in java and witing a programm to delete an element with specific position. I know there are many possible answer but i am trying here my own. I am getting the error :

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 9
                                at 
Array.DeleteElement.delete(DeleteElement.java:24)
                                at 
Array.DeleteElement.main(DeleteElement.java:14)

Now Here I am passing array and position. Where it is getting incorrect index. As per documentaion it is saying array has been accessed with an illegal index. Can anybody please explain me how it is illegal and where I am getting wrong.

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    //int[] delArray = new int[15]; 
    int[] delArray = {20,50,60,9,8,7,1,5,3};
    System.out.println("Enter Element you want to delete");
    int del = in.nextInt();
    int pos = InsertSearch.searchKey(delArray,del);
    System.out.println(pos);
    if(pos != -1){
        delete(delArray,del,pos);
        for(int i=0; i<delArray.length; i++)
            System.out.println(delArray[i]);
    }
    else 
        System.out.println(del+"Not exist in array");
}

public static int delete(int delArr[], int del, int pos){
    for(int i=pos; i<delArr.length; i++)
        delArr[i] = delArr[i+1];
    return delArr.length -1;
}

score 1 · Answer 1 · answered Apr 18 '17 at 17:03

1

Here

delArr[i] = delArr[i+1];

When i is equal to 8, then i+1 gives 9, which generates the Exception

answered Apr 18 '17 at 17:03

dumbPotato21

5,669
5
21
34

score 1 · Accepted Answer · answered Apr 18 '17 at 17:03

1

Look,

public static int delete(int delArr[], int del, int pos){
    for(int i=pos; i<delArr.length; i++)
        delArr[i] = delArr[i+1];   //<---- HERE
    return delArr.length -1;
}

in this loop, i goes up to the max index of the array, but inside, you access i+1th element which in this case causes IndexOutOfBoundsException being thrown.

From the stacktrace, you can read, that you tried to access 9th element but your array has only indexes from 0 to 8 incl.

answered Apr 18 '17 at 17:03

xenteros

15,586
12
56
91

Oh.. got it. It means when it try to access for last index `del[i+1]` is not getting. perfect explanation. thanks – shanky singh Apr 18 '17 at 17:06
I am sorry but I don't how to read stack trace. any link for that will be helpfull. – shanky singh Apr 18 '17 at 17:07
@shankysingh http://stackoverflow.com/questions/3988788/what-is-a-stack-trace-and-how-can-i-use-it-to-debug-my-application-errors – xenteros Apr 18 '17 at 17:08
Ya, I got the desire result. Will accept answer after 8 min :) – shanky singh Apr 18 '17 at 17:08
@shankysingh cool, thanks. Also, pro-tip - use brackets even if they aren't obligatory. Wrap {single line} – xenteros Apr 18 '17 at 17:09

score 1 · Answer 3 · answered Apr 18 '17 at 17:11

This snippet of code is problem

for(int i=pos; i<delArr.length; i++)
    delArr[i] = delArr[i+1];

Precisely, delArr[i] = delArr[i+1]. The issue is i+1.
In Java indices in an array starts with 0, and the last index is N-1 for the array which has length N. You loop should be for(int i=pos; i<delArr.length-1; i++).

How array has been accessed with an illegal index

3 Answers3