DatagramSocket read and write methods

Question

Hi,
I am trying to implement a client/server schame via NIO DatagramChannel.
I manage to make it work with the methods send/receive. but i am not able to make it work in "connected" mode via write/read method.
i bind and connect like this;
this.channel = DatagramChannel.open();
this.channel.configureBlocking(false);
this.channel.socket().bind(hostAdr);
this.channel.connect(destAddress);
then i receive messages like this:
ByteBuffer theReceiveDataByteBuffer = ByteBuffer.allocateDirect(5000);
Charset charset = Charset.forName("ISO-8859-1");
StringBuffer buffer = new StringBuffer();
String[] retval = new String[2];
while (flag) {
try {
Int value = receiverChannel.read(theReceiveDataByteBuffer);
long time = System.currentTimeMillis();
} catch (IOException e) {
Thread.currentThread().interrupt();
flag = false;
I send via the write method, it seems i manage to send but i receive nothing...
How to code this kind of scheme with write/read ?
thank you
Sebastien
Edited by: sepi_seb on Nov 29, 2007 10:06 AM

Answer 1

Well (a) you're spinning madly burning up the CPU in a non-blocking read loop; (b) if this is the complete code you don't have any way of knowing whether you received anything or not; and (c) you're completely suppressing any IOExceptions that may be occurring, so you can't see anything that's going wrong.
So:
(a) don't use non-blocking mode, or use a Selector to tell you when OP_READ is ready for the channel;
(b) try breaking out of the loop when you've received something, i.e. when the bytecount returned from read() > 0; and then display something;
(c) when you get an exception it contains a valuable message and an equally valuable stack trace. Don't just ignore them.