Question

I’m using array of bytes to store data packet received from another computer.

receivedData = new byte[1024];
receivedPacket = new DatagramPacket(receivedData, receivedData.length);
socket.receive(receivedPacket);
receivedData = receivedPacket.getData();
String res = new String(receivedData);  // PROBLEM HERE

the problem is at last line: because I declare receivedData as a byte stream with length 1024. so, always last line will create a new string from whole array, although it doesn’t know exactly how many real byte I received. So, I meet frustrated error: res is not received as I wish. (because length of real bytes that I received not fix whole array)

So, my question is: how can I fix this point, how can I know how many bytes I really received to convert to string?

Answer 1

Try using DatagramPacket.getLength().

receivedData = new byte[1024];
receivedPacket = new DatagramPacket(receivedData, receivedData.length);
socket.receive(receivedPacket);
receivedData = receivedPacket.getData();
String charsetName = "US-ASCII"; // set to desired charset
String res = new String(receivedData, 0, receivedPacket.getLength(), charsetName);

Edited to add charset. Thanks, parsifal.