DatagramPacket on MulticastSocket

Question

Im trying to Send out a DatagramPacket on a MulticastSocket. This bit is working but when i try and get the info out of the header its not working.

while(true){
         byte[] packet = new byte[1500];

        DatagramPacket packetR = new DatagramPacket(packet, packet.length);
        socketM.receive(packetR);
         ByteBuffer data = ByteBuffer.wrap(packetR.getData());
         byte[] senderAddress = new byte[100];
         byte[] senderCommand =new byte[100];


        data.get(senderAddress,0,4);
        InetAddress senderIP = InetAddress.getByAddress(senderAddress);

         data.position(4); 
         data.get(senderCommand,0,1);
        String command = (char)senderCommand[0]+"";


        System.out.print(senderIP+":  "+ command+"\n");



        }

This works but i just get all of it printed out

while(true){
         byte[] packet = new byte[100];
        DatagramPacket packetR = new DatagramPacket(packet, packet.length);
        socketM.receive(packetR);
        InetAddress ip = packetR.getAddress();

        String meg = new String(packetR.getData());
        System.out.print(ip+":  "+ meg+"\n");



        }

Can anyone see why this would not work thanks.

what do you mean with "is not working"? is it throwing exception? is it telling something? be specific — Gianmarco, Sep 15 '13 at 08:31
what's the problem then with the second code you posted? "I just get all of it printed out" means that in `ip` and `meg` you have the values you need... — Gianmarco, Sep 15 '13 at 08:39
meg has more then i need i need to get the 4th Byte out to use it for a test. — 1ftw1, Sep 15 '13 at 08:43

user207421 · Answer 1 · 2017-05-02T00:11:49.670

0

The fourth byte of data is given by packet.getData()[3].

If that doesn't answer as clarified in your comments you will have to clarify further.

edited May 02 '17 at 00:11

answered Oct 16 '13 at 21:45

user207421

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DatagramPacket on MulticastSocket

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