Trouble with applet tutorial about servers

Question

I downloaded the sources of this (http://java.sun.com/docs/books/tutorial/deployment/applet/clientExample.html) example and am trying to make them work. However I'm having trouble with the server program.It compiles fine but when I run it I get NullPointerException in QuoteServerThread class on this line:
packet = new DatagramPacket(buf, 256);buf is a byte array and it's set to null.
I don't have any experience with networking in java so if the problem is something really simple you'll know why I didn't find it.
Oh, and the code of the thread is here http://java.sun.com/docs/books/tutorial/deployment/applet/examples/QuoteServerThread.java

Answer 1

Replace
byte[] buf = null;with
byte[] buf = new byte[ 256 ];Other problems may happen if this sample was not tested properly.
The problem is that the DatagramPacket requires you to supply a non-null buffer, as per:
DatagramPacket
public DatagramPacket(byte[] buf, int length)
Constructs a DatagramPacket for receiving packets of length length.
The length argument must be less than or equal to buf.length.
Parameters:
buf - buffer for holding the incoming datagram.
length - the number of bytes to read.
Edited by: baftos on Jul 18, 2008 3:38 PM