Socket & Networking Programming

ARP :

    import java.net.InetAddress;

    import java.net.NetworkInterface;

    import java.net.SocketException;

    import java.net.UnknownHostException;

    import java.util.Scanner;

    

    public class MacAddress {

            public static void main(String[] args){

                        try{                 

    Scanner console = new Scanner(System.in);

    System.out.println("Enter System Name: ");

    String ipaddr = console.nextLine();

    InetAddress address = InetAddress.getByName(ipaddr);

    System.out.println("address = "+address);

    NetworkInterface ni = NetworkInterface.getByInetAddress(address);

   

    if (ni!=null){

            byte[] mac = ni.getHardwareAddress();

            if (mac!= null){

            System.out.print("MAC Address : ");

            for (int i=0; i<mac.length; i++){

            System.out.format("%02X%s", mac[i], (i<mac.length - 1) ? "-" :"");

            }

    }

    else{

            System.out.println("Address doesn't exist or is not accessible/");

            }

    } 

else{

            System.out.println("Network Interface for the specified address is not found");

            }

  }

  catch(Exception e){   }

  }

}

OUTPUT:

UDP Chat Application

MyClient.java  :

import java.io.*;

import java.net.*;

public class MyClient {

public static void main(String[] args) {

try{     

Socket s=new Socket("localhost",6666);      

DataOutputStream dout=new DataOutputStream(s.getOutputStream());

dout.writeUTF("Hello Server");

dout.flush();

dout.close();

s.close();

}catch(Exception e){System.out.println(e);}

}

}

MyServer.java :

import java.io.*;

import java.net.*;

public class MyServer {

public static void main(String[] args){

try{

ServerSocket ss=new ServerSocket(6666);

Socket s=ss.accept();//establishes connection

DataInputStream dis=new DataInputStream(s.getInputStream());

String  str=(String)dis.readUTF();

System.out.println("message= "+str);

ss.close();

}catch(Exception e){System.out.println(e);}

}

}