Java ServerSocket create

import java.io.BufferedReader;
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 serverSocket = new ServerSocket(6789);
      // wait for incoming connection SOCKET PROGRAMMING 299
      System.out.println("Server is listening on port 6789");
      Socket serverEnd = serverSocket.accept();
      System.out.println("Request accepted");
      // get streams
      BufferedReader fromClient = new BufferedReader(new InputStreamReader(serverEnd.getInputStream()));
      PrintWriter toClient = new PrintWriter(serverEnd.getOutputStream(), true);
      // receive data from client
      int n = Integer.parseInt(fromClient.readLine());
      System.out.println("Received from client: " + n);
      int fact = 1;
      for (int i = 2; i <= n; i++)
         fact *= i;/*from  w  w  w  .j  a v a  2 s. c o  m*/
      // send result to the client
      toClient.println(fact);
      System.out.println("Sent to client: " + fact);
      serverSocket.close();
   }
}

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class Main {
  public static void main(String[] args) throws Exception {
    // Create a Server socket
    ServerSocket serverSocket = new ServerSocket(12900, 100, InetAddress.getByName("localhost"));
    System.out.println("Server started at: " + serverSocket);

    // Keep accepting client connections in an infinite loop
    while (true) {
      System.out.println("Waiting for a connection...");

      // Accept a connection
      final Socket activeSocket = serverSocket.accept();

      System.out.println("Received a connection from " + activeSocket);

      // Create a new thread to handle the new connection
      Runnable runnable = () -> {
        try {// ww  w .j  a va2s .  c om
          handleClientRequest(activeSocket);
        } catch (Exception e) {
          e.printStackTrace();
        }
      };

      new Thread(runnable).start(); // start a new thread
    }
  }

  public static void handleClientRequest(Socket socket) throws Exception {
    BufferedReader socketReader = null;
    BufferedWriter socketWriter = null;

    // Create a buffered reader and writer for the socket
    socketReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    socketWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));

    String inMsg = null;
    while ((inMsg = socketReader.readLine()) != null) {
      System.out.println("Received from client: " + inMsg);

      // Echo the received message to the client
      String outMsg = inMsg;
      socketWriter.write(outMsg);
      socketWriter.write("\n");
      socketWriter.flush();
    }
    socket.close();
  }
}