Program to implement Quick Sort (Recursive)

import java.io.DataInputStream;   // to load DataInputStream class 
          
class QuickSortRec
{
public static void main(String args[ ])
{
int i,n=0;
  int x[]=new int[25];
DataInputStream in = new DataInputStream(System.in); 


                try
{
   System.out.print("Enter how many numbers to be sorted : ");
                   n = Integer.parseInt(in.readLine());
                    System.out.println("Enter "+n+" numbers in any order....");
                    for(i=0;i<n;i++)
                    {
                  System.out.print("\t\tElement x["+(i+1)+"]=");
                   x[i] = Integer.parseInt(in.readLine());
                    }
}
catch(Exception e) {  System.out.println("I/O Error");   }

                quicksort(x,0,n-1,n);  // Call to recursive quick sort
          System.out.println("\nSorted Elements are :");
System.out.println("-----------------------------------");
                display(x,n);
System.out.println("-----------------------------------");
         }




//Recursive quick Sort Function


static void quicksort(int x[], int lb, int ub, int n)
{
int j=0;
if(lb>=ub)
  return;
j=partition(x, lb, ub, j);
System.out.println("After partitioning array from index "+(lb+1)+" to "+(ub+1)+ " :\n ");
display(x,n);
quicksort(x, lb, j-1, n);
quicksort(x, j+1, ub, n);
} // end of recursive quick sort function


static int partition(int x[], int lb, int ub, int pj)
{
int a, down, temp, up;
a=x[lb];               // a is pivot element
      up=ub;
       down=lb;
while(down<up)
{
while(x[down]<=a && down<up)
down=down+1;        //move up the array
    while(x[up]>a)
up=up-1;          //move down the array
    if(down<up)
      {
temp=x[down];    //interchange x[down]with x[up]
x[down]=x[up];
x[up]=temp;
       }/*end if*/
    }/* end while*/
           x[lb]=x[up];
       x[up]=a;
                pj=up;
return (pj);
}/* end partition*/


static void display(int x[], int n)
{
int i;
System.out.println(" ");
for(i=0;i<n;i++)
System.out.print("\t"+x[i]+ " ");
System.out.println(" ");
} // end of display function


}