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Java in a Nutshell

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The java.net Package

28.12 java.net.MulticastSocket (JDK 1.1)

This subclass of DatagramSocket is used to send and receive multicast UDP packets. It extends DatagramSocket by adding joinGroup() and leaveGroup() methods to join and leave multicast groups. The IP address specified to these methods should be a valid multicast address in the range of to Note that you do not have to join a group to send a packet to a multicast address, but you must join the group to receive packets sent to that address.

MulticastSocket defines a variant send() method that allows you to specify a time-to-live (TTL) value for the packet you send. This value specifies the number of network "hops" the packet may travel before it expires. You can also set a default TTL for all packets sent though a MulticastSocket with setTTL().

Note that untrusted applets are not allowed to use multicast sockets.

public class MulticastSocket extends DatagramSocket {
    // Public Constructors
            public MulticastSocket() throws IOException;
            public MulticastSocket(int port) throws IOException;
    // Public Instance Methods
            public InetAddress getInterface() throws SocketException;
            public byte getTTL() throws IOException;
            public void joinGroup(InetAddress mcastaddr) throws IOException;
            public void leaveGroup(InetAddress mcastaddr) throws IOException;
            public synchronized void send(DatagramPacket p, byte ttl) throws IOException;
            public void setInterface(InetAddress inf) throws SocketException;
            public void setTTL(byte ttl) throws IOException;



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