The java.nio.channels package supports only unicast datagram sockets.
It should be extended to support multicast datagram sockets.
-- ###@###.### 2002/2/20
This has been integrated into jdk7 build 36 via 4640544.
As part of NIO.2/JSR-203 we have added multicast support to DatagramChannel. This allows a DatagramChannel to join a multicast group to receive all multicast datagrams sent to the group, or to join the group so that it only receives multicast datagrams sent by specific sources.
This feature will be deliverved by JSR-203 ("NIO.2"). This JSR is targetting Dolphin (Java SE 7).