Java Sockets - Client and Server

Creating a socket server and socket client is easy as below.

Server

import java.net.*;

import java.io.*;

public class KnockKnockServer

{

public static void main (String a[])

{

        int portNumber = Integer.parseInt(a[0]);

        try

        {

             ServerSocket serverSocket = new ServerSocket(portNumber);

             Socket clientSocket = serverSocket.accept();

             PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

             BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

             String inputLine, outputLine;

            

            // Initiate conversation with client

            KnockKnockProtocol kkp = new KnockKnockProtocol();

            outputLine = kkp.processInput(null);

            out.println(outputLine);

            

            while ((inputLine = in.readLine()) != null) {

                outputLine = kkp.processInput(inputLine);

                out.println(outputLine);

                if (outputLine.equals("Bye."))

                    break;

            }

        }

        catch (Exception ex)

        {

            ex.printStackTrace();

        }

}

}

Client 

Client is pretty simple as well, just give the hostname and the ip at which the server listens. 

String hostName = args[0];

int portNumber = Integer.parseInt(args[1]);

try (

Socket kkSocket = new Socket(hostName, portNumber);

PrintWriter out = new PrintWriter(kkSocket.getOutputStream(), true);

BufferedReader in = new BufferedReader(

new InputStreamReader(kkSocket.getInputStream()));

)

references:

http://docs.oracle.com/javase/tutorial/networking/sockets/clientServer.html