Getting exception when using foreach but regular for loop executes well

Question

Using regular foloop, getting correct output, using for each loop throws ArrayOutOfBound exception. Can anyone explain?

public class FindTheDiff {
public static void main(String args[]){
    System.out.println(isAnagramRecursion("all","laa"));
}

private static boolean isAnagramRecursion(String param1, String param2) {
    int[] arr = new int[122];
    char[] param1Lower = param1.toLowerCase().toCharArray();
    char[] param2Low2 = param2.toLowerCase().toCharArray();

    for (char ch1 : param1Lower) {
        arr[ch1] = arr[ch1]+1;
    }

    for (char ch2 : param2Low2){
        arr[ch2] = arr[ch2]-1;
    }

    for (int i :arr) {
        if(arr[i] != 0)
            return false;
    }
    /*for (int i = 0; i < arr.length; i++) {
        if(arr[i] != 0)
            return false;
    }*/
    return true;
}

}

RUARO Thibault · Accepted Answer · 2020-07-25 13:55:03Z

2

This is the wrong loop. When doing a forEach loop, you iterate over the value, not the index. The correct forEach loop in your case should be:

for (int arrValue :arr) {
    if(arrValue != 0)
        return false;
}

answered Jul 25, 2020 at 13:55

RUARO Thibault

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Comments

Eklavya · Accepted Answer · 2020-07-25 14:01:56Z

1

Here i is not the index of the array, it's the value of the array. But in the regular loop i is the index.

for (int i :arr) {
    if(arr[i] != 0)
       return false;
}

Use the value of the array means i in if condition

for (int i :arr) {
    if(i != 0)
        return false;
}

edited Jul 25, 2020 at 14:01

answered Jul 25, 2020 at 13:55

Eklavya

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