QuickSort.java

static void swap(int[] arr, int i, int j) {
  int temp = arr[i];
  arr[i] = arr[j];
  arr[j] = temp;
}

static int partition(int[] arr, int low, int high) {
  // Pick pivot
  int pivot = arr[high];

  // Index of smaller element and indicates the right position of pivot found so far
  int i = (low - 1);

  for(int j = low; j <= high - 1; j++) {
    // If current element is smaller than the pivot
    if (arr[j] < pivot) {
      i++;
      swap(arr, i, j);
    }
  }
  swap(arr, i + 1, high);
  return (i + 1);
}

static void quickSort(int[] dataCollection, int low, int high) {
  if (low < high) {
    // p is partitioning index, arr[p] is now at right place
    int p = partition(dataCollection, low, high);
    // Separately sort elements before partition and after partition
    quickSort(dataCollection, low, p - 1);
    quickSort(dataCollection, p + 1, high);
  }
}