/**
 *  data-gram
 */
import java.io.*;
import java.net.*;

public class MPacketSender {
    // port
    private static final int PORT = 55524;

    // message
    private static String message ="Can you receive this packet?";

    /**
     *  send
     */
    protected void send(String[] argv){
        try {
            MulticastSocket socket = new MulticastSocket( PORT );
            InetAddress group    = InetAddress.getByName( argv[0] );
            socket.joinGroup( group );
            
            byte[] data = message.getBytes();
            DatagramPacket packet= new DatagramPacket( data, data.length, group, PORT );
            socket.send( packet );
            System.out.println( "Send packet done." );

            socket.leaveGroup(group);
        }catch( ArrayIndexOutOfBoundsException e ) {
            System.err.println("Usage:java HostAddress hostname");
        }catch( UnknownHostException e ) {
            System.err.println( "Server not Found" );
        }catch( SocketException e ) {
            System.err.println( "Socket Error" );
        }catch( IOException e ) {
            System.err.println( "IO Error" );
        }
    }

    /**
     *  Main method
     */
    public static void main( String argv[] ) {
        MPacketSender sender=new MPacketSender();
        sender.send(argv);
    }
}