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javaechodatagram

Can a received DatagramPacket be used to be sent again?

I am testing a UDP echo server, is the following code correct?

DatagramSocket s = ...
DatagramPacket p = new DatagramPacket(new byte[512], 512);

...

s.recieve(p);
s.send(p);

My question is, can I send the DatagramPacket just as I recieved it? According to the java specification, the contructor I used constructs a DatagramPacket 'for recieving use'. I am not sure if that state changes when the packet has been modified through s.recieve, or if that 'for recieve use state' is permanent.

If the code is correct, is there any reason why in the tutorial they construct a whole new DatagramPacket? (maybe just clarity?) https://docs.oracle.com/javase/tutorial/networking/datagrams/clientServer.html

Solution

  • Yes, and it's quite common. If you receive a request, the DatagramPacket already has the return address in it, so all you need to do is put the response data into it and send it back.