Quick Sort Java Code

 /*  
  * QuickSort  
  * Best case performance             O(n log(n))  
  * Average case performance          O(n log(n))  
  * Worst case performance            O(n^2)  
  * Worst case space complexity       O(log(n))  
  */  
 public class QuickSortExample {  
      public static void main(String[] args) {  
           int[] array= {4,2,3,5,6,9};  
           recursiveQuickSort(array, 0, array.length-1);  
           for(int i:array){  
                System.out.println(i+" ");  
           }  
      }  
      private static void recursiveQuickSort(int[] array, int startIdx, int endIdx){  
           int idx = partition(array, startIdx, endIdx);  
           if(startIdx < idx-1){  
                recursiveQuickSort(array, startIdx, (idx-1));  
           }  
           if(endIdx > idx){  
                recursiveQuickSort(array, idx, endIdx);  
           }  
      }  
      private static int partition(int[] array, int leftPtr, int rightPtr){  
           int pivot = array[leftPtr];  
           while(leftPtr <= rightPtr){  
                while(array[leftPtr] < pivot){  
                     leftPtr++;  
                }  
                while(array[rightPtr]>pivot){  
                     rightPtr--;  
                }  
                if(leftPtr<=rightPtr){  
                     int tmp = array[leftPtr];  
                     array[leftPtr] = array[rightPtr];  
                     array[rightPtr] = tmp;  
                     leftPtr++;  
                     rightPtr--;  
                }  
           }  
           return leftPtr;  
      }  
 }