Question

Write a program that shows the operation of TCP/IP socket. (Java)

Please if you can, put a comment to let me understand the code better.

Answer 1

// A Java program for a Client

//Here we see how the TCp/IP Socket works

/** Here in Socket socket = new Socket(“127.0.0.1”, 5000).

Here the first argument is the IP address of Server. ( 127.0.0.1 is the IP address of localhost, where code will run on single stand-alone machine). Here you should ideally check your ipadress from ipconfig command in command prompt and replace it.

Second argument – TCP Port. (Just a number representing which application to run on a server. For example, HTTP runs on port 80. Port number can be from 0 to 65535)

**/

import java.net.*;

import java.io.*;

  

public class Client

{

    // initialize socket and input output streams

    private Socket socket            = null;

    private DataInputStream input   = null;

    private DataOutputStream out     = null;

  

    // constructor to put ip address and port

    public Client(String address, int port)

    {

        // establish a connection

        try

        {

            socket = new Socket(address, port);

            System.out.println("Connected");

  

            // takes input from terminal

            input = new DataInputStream(System.in);

  

            // sends output to the socket

            out    = new DataOutputStream(socket.getOutputStream());

        }

        catch(UnknownHostException u)

        {

            System.out.println(u);

        }

        catch(IOException i)

        {

            System.out.println(i);

        }

  

        // string to read message from input

        String line = "";

  

        // keep reading until "Over" is input

        while (!line.equals("Over"))

        {

            try

            {

                line = input.readLine();

                out.writeUTF(line);

            }

            catch(IOException i)

            {

                System.out.println(i);

            }

        }

  

        // close the connection

        try

        {

            input.close();

            out.close();

            socket.close();

        }

        catch(IOException i)

        {

            System.out.println(i);

        }

    }

  

    public static void main(String args[])

    {

//Do not forget to replace Ip and Port in the next line

Client client = new Client("127.0.0.1", 5000);

    }

}