QUICK SORT EXAMPLE PROGRAM IN JAVA

 /*  
 QuickSort:   
 This sort can be done in different ways ..........  
 I have taken Pivot as middle element.   
 you can take any element as Pivot.   
 Author: itafiz@gmail.com  
 */  
 class SortQuick  
 {  
      public static void main(String[]args)  
      {  
       int i;  
       int array[] = {12,9,4,99,1};  
       System.out.println("Elements Before Sort:\n");  
       for(i = 0; i < array.length; i++)  
         System.out.print( array[i]+" ");  
        System.out.println();  
       quickSort(array,0,array.length-1);  
      System.out.println("Elements Before Sort:\n");  
       for(i = 0; i < array.length; i++)  
         System.out.print( array[i]+" ");  
        System.out.println();  
      }  
 public static void quickSort(int a[],int low, int len)  
      {  
      if(low>=len) return; // checking if length of the array is Zero.   
      int l=low,n=len; //initialization  
      int piv=a[(l+n)/2]; // middle element  
      while(l<n)//--------------------------1  
           {  /**  
             moving upto less than pivot value from start.   
             */  
                while(l<n && a[l]<piv)   
                     l++;   
             /**  
             moving upto greater than pivot value from end.   
             */  
                while(l<n && a[n]>piv)  
                     n--;   
             /**  
             swap in order to move least elements to left and maximum to right  
             of the pivot.   
             */  
               if(l<n){  
                 int tem = a[l];  
                 a[l]=a[n];  
                 a[n]=tem; }             
           }// end of while loop----------1  
           if(n<l)// checking start and end index(start must be less than end otherwise swap)   
           {  
            int t = l;l=n;n=t;   
           }  
           quickSort(a,low,l);// sort left part of the array.   
           quickSort(a,l==low?l+1:l,len); //sorting right part of the array  
      }  
 }