Rebinding a port to datagram socket on a difftent IP

To avoid exceptions when trying to unbind and rebind, you would set each created socket as reusable. In order to do so, you MUST create an unbound socket:

DatagramSocket s = new DatagramSocket(null);
s.setReuseAddress(true);
s.bind(someSocketAddress);

More info: http://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#setReuseAddress(boolean)

P.S. The timeout period that is the main reason for a BindException under such circumstances when using a TCP may not apply to UDP sockets, but the SO_REUSE should allow you to rebind instantly anyway. http://docs.oracle.com/javase/7/docs/api/java/net/DatagramSocket.html#setReuseAddress(boolean)

Here are a few examples:

final int port = 55880;

A) No reuse, no close = Address already in use

DatagramSocket s = new DatagramSocket(null);
s.bind(new InetSocketAddress("127.0.0.1", port));

s = new DatagramSocket(null);
s.setReuseAddress(true);
s.bind(new InetSocketAddress("localhost", port));

B) Reuse, no close = no complaints

DatagramSocket s = new DatagramSocket(null);
s.setReuseAddress(true);
s.bind(new InetSocketAddress("127.0.0.1", port));

s = new DatagramSocket(null);
s.setReuseAddress(true);
s.bind(new InetSocketAddress("localhost", port));

C) No reuse, close = no complaints (for datagram sockets only)

DatagramSocket s = new DatagramSocket(null);
s.bind(new InetSocketAddress("127.0.0.1", port));
s.close();

s = new DatagramSocket(null);
s.bind(new InetSocketAddress("localhost", port));
s.close();