Sub array which forms the given sum

Given an unsorted array of nonnegative integers, find a continous subarray which adds to a given number.

 private static void checkSumExists(int[] a, int pRequiredSum) {
  int length = a.length;
  int currentSum = a[0];
  int startIndex = 0;

  for (int i = 1; i < length; i++) {
   while (currentSum > pRequiredSum && startIndex<i-1) {
    currentSum = currentSum - a[startIndex];
    startIndex++;
   }

   if (currentSum == pRequiredSum) {
    System.out.println("SubArray with startIndex : " + startIndex
      + " and endIndex : " + (i - 1)
      + " makes the given sum :" + pRequiredSum);
    return ;
   }

   currentSum = currentSum + a[i];
  }

  System.out
    .println("Sub array which makes the required sum doesn't exist : "
      + pRequiredSum);
 }

Refer : http://www.geeksforgeeks.org/archives/19267