For-Each Loop Java Error ArrayIndexOutOfBoundsException

Question

In my program I need a for-each loop which counts the number of evens in the given array and increments the variable even for each one. When I use a standard for loop, i.e. (i = 0; i < numbers.length; i++;), then the code works fine. However, my assignments requires me to use a for-each loop for this particular problem. Am I doing something wrong?

int [] numbers = new int[8];
int even = 0;
int odd = 0;

for (int i = 0; i < numbers.length; i++) { 
    numbers[i] = (int)(Math.random() * 51 + 50);
}

for (int i : numbers) {
    if (numbers[i] % 2 == 0) {
        even++;
    }
    else
        odd++;

This throws up the error:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 54

Answer 1

if (numbers[i] % 2 == 0) {

Inside your foreach loop, you need not to access it with index. Just i is enough as foreach keep on gives you the element directly (not the index) inside the array/collection you are using.

if (i % 2 == 0) {

---

for (int i : numbers) {
        if (i % 2 == 0) {
            even++;
        }
        else{
            odd++;
        }
  }

---

You can actually shorten your codes by eliminating the second loop completely by checking the even or odd in first loop itself.

Answer 2

For each loop in your case will be explained like:

for (int i : numbers) {

every integer in array numbers will be placed in i one by one

so,what you are doing wrong is:

if (numbers[i] % 2 == 0) {

for (int i : numbers) {
if (numbers[i] % 2 == 0) {
even++;
}
else {
odd++;
} 

i will not be increasing evrytime loop proceed like in the traditional for loop, here i carry the actual value

so you should change from numbers[i]%2==0 to just i%2==0

 for (int i : numbers) {
if (i % 2 == 0) {
    even++;
}
else {
    odd++;
  }