tcp

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

public class myserver
{

    private static Socket socket;

    public static void main(String[] args)
    {
        try
        {
            int port = 25000;
            ServerSocket serverSocket = new ServerSocket(port);
            System.out.println("Server Started and listening to the port 25000");

            //Server is running always. This is done using this while(true) loop
            while(true)
            {
                //Reading the message from the client
                socket = serverSocket.accept();
                InputStream is = socket.getInputStream();
                InputStreamReader isr = new InputStreamReader(is);
                BufferedReader br = new BufferedReader(isr);
                String number = br.readLine();
                System.out.println("Message received from client is "+number);


                //Multiplying the number by 2 and forming the return message
                String returnMessage;
                try
                {
                    int numberInIntFormat = Integer.parseInt(number);
                    System.out.println("Enter no. to multiply");

                    int returnValue = numberInIntFormat*2;
                    returnMessage = String.valueOf(returnValue) + "\n";
                }
                catch(NumberFormatException e)
                {
                    //Input was not a number. Sending proper message back to client.
                    returnMessage = "Please send a proper number\n";
                }

                //Sending the response back to the client.
                OutputStream os = socket.getOutputStream();
                OutputStreamWriter osw = new OutputStreamWriter(os);
                BufferedWriter bw = new BufferedWriter(osw);
                bw.write(returnMessage);
                System.out.println("Message sent to the client is "+returnMessage);
                bw.flush();
            }
        }
        catch (Exception e){}
    }
    }
/*import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.Socket;

public class myclient
{

    private static Socket socket;

    public static void main(String args[])
    {
        try
        {
            String host = "localhost";
            int port = 25000;
            InetAddress address = InetAddress.getByName(host);
            socket = new Socket(address, port);

            //Send the message to the server
            OutputStream os = socket.getOutputStream();
            OutputStreamWriter osw = new OutputStreamWriter(os);
            BufferedWriter bw = new BufferedWriter(osw);
            System.out.print("Enter no.");
            BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
            String number = stdin.readLine();;
            String sendMessage = number + "\n";
            bw.write(sendMessage);
            bw.flush();
            System.out.println("Message sent to the server : "+sendMessage);

            //Get the return message from the server
            InputStream is = socket.getInputStream();
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader br = new BufferedReader(isr);
            String message = br.readLine();
            System.out.println("Message received from the server : " +message);
        }
        catch (Exception exception)
        {
            exception.printStackTrace();
        }
        finally
        {
        try
         {
         socket.close();
          }
          catch(Exception e)
         {
           e.printStackTrace();
        }
    }
    }
}

*/