Java MulticastSocket .joinGroup (SocketAddress mcastaddr, NetworkInterface netIf)

public void joinGroup(SocketAddress mcastaddr,  NetworkInterface netIf)  throws IOException

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import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.MulticastSocket;
import java.net.NetworkInterface;

public class Main {
  public static void main(String[] args) throws Exception {
    int port = 0;
    byte ttl = (byte) 1;

    byte[] data = "Here's some multicast data\r\n".getBytes();
    DatagramPacket dp = new DatagramPacket(data, data.length, InetAddress.getByName("google.com"), port);

    MulticastSocket ms = new MulticastSocket(InetSocketAddress.createUnresolved("google.com", 8080));
    ms.joinGroup(InetSocketAddress.createUnresolved("127.0.0.1",8080),NetworkInterface.getByIndex(0));
    for (int i = 1; i < 10; i++) {
      ms.send(dp, ttl);
    }
    ms.leaveGroup(InetAddress.getByName("google.com"));

    
    ms.close();
  }

}