Simple version of quick sort

 
public class QuickSortSimpleVersion {
  private long[] data;

  private int len;

  public QuickSortSimpleVersion(int max) {
    data = new long[max];
    len = 0;
  }

  public void insert(long value) {
    data[len] = value;
    len++;
  }

  public void display() {
    System.out.print("Data");
    for (int j = 0; j < len; j++)
      System.out.print(data[j] + " ");
    System.out.println("");
  }

  public void quickSort() {
    recQuickSort(0, len - 1);
  }

  public void recQuickSort(int left, int right) {
    if (right - left <= 0) // if size <= 1 already sorted
      return;
    else // size is 2 or larger
    {
      long pivot = data[right]; // rightmost item
      // partition range
      int partition = partitionData(left, right, pivot);
      recQuickSort(left, partition - 1); // sort left side
      recQuickSort(partition + 1, right); // sort right side
    }
  }

  public int partitionData(int left, int right, long pivot) {
    int leftPtr = left - 1; // left (after ++)
    int rightPtr = right; // right-1 (after --)
    while (true) { // find bigger item
      while (data[++leftPtr] < pivot)
        ;
      // find smaller item
      while (rightPtr > 0 && data[--rightPtr] > pivot)
        ;

      if (leftPtr >= rightPtr) // if pointers cross, partition done
        break;
      else
        swap(leftPtr, rightPtr);
    }
    swap(leftPtr, right); // restore pivot and return pivot location
    return leftPtr;
  }

  public void swap(int d1, int d2) {
    long temp = data[d1];
    data[d1] = data[d2];
    data[d2] = temp;
  }

  public static void main(String[] args) {
    int maxSize = 16; // array size
    QuickSortSimpleVersion arr = new QuickSortSimpleVersion(maxSize); // create array

    for (int j = 0; j < maxSize; j++) // fill array with random numbers
    {
      long n = (int) (java.lang.Math.random() * 99);
      arr.insert(n);
    }
    arr.display();
    arr.quickSort();
    arr.display();
  }

}