Java ServerSocket handle client using thread

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Main {
   public static void main(String argv[]) throws Exception {
      // create a server socket at port 6789
      ServerSocket welcomeSocket = new ServerSocket(6789);
      System.out.println("Server ready");
      while (true) {
         // wait for incoming connection
         Socket serverEnd = welcomeSocket.accept();
         System.out.println("Request accepted");
         // hand over this connection request to Handler
         new Handler(serverEnd);
      }/* w w  w. j  a  va2  s  .  c  o m*/
   }
}

class Handler implements Runnable {
   Socket serverEnd;
   Handler(Socket s) {
      this.serverEnd = s;
      new Thread(this).start();
      System.out.println("A thread created");
   }

   public void run() {
      try {
         // get streams
         BufferedReader fromClient = new BufferedReader(new InputStreamReader(serverEnd.getInputStream()));
         PrintWriter toClient = new PrintWriter(serverEnd.getOutputStream(), true);
         while (true) {
            // receive data from client
            int n = Integer.parseInt(fromClient.readLine());
            System.out.println("Received " + n);
            if (n == -1) {
               serverEnd.close();
               break;
            }
            int fact = 1;
            for (int i = 2; i <= n; i++)
               fact *= i;
            // send result to the client
            toClient.println(fact);
            System.out.println("Sent: " + fact);
         }
      } catch (IOException e) {
      }
   }
}