Question

Everytime I try to send a UDP packet to an address I get the following exception:

java.lang.ArrayIndexOutOfBoundsException
    at java.net.PlainDatagramSocketImpl.send(Native Method)
    at java.net.DatagramSocket.send(DatagramSocket.java:625)
    at services.servicetypes.network.host.Server_UDP_Thread_Monitor.send(Server_UDP_Thread_Monitor.java:84)

Which points directly to the socket send function – this.socket.send(packet);

After placing a break point on my datagram packet I get the following info:

packet  DatagramPacket  java.net.DatagramPacket@52c4c57 
byte[]  #1248(length=16)    
offset  int 0   
length  int 16  
bufLength   int 16  
address Inet4Address    /192.168.0.101  
Static          
Inherited   
port    int 3889

I’m not clear on why this is occuring, if anyone could shed any light on the problem that would be great. My inital thoughts were perhaps one of the datagram packet elements was empty.

(Basic source)

ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
DataOutputStream out = new DataOutputStream(byteOut);

// Game type
out.writeInt(1);

// Client
out.writeInt(gamerToSend.getClientID());

// Position
out.writeFloat(gamerToSend.getX());
out.writeFloat(gamerToSend.getY());


DatagramPacket packet = new DatagramPacket
(
  byteOut.toByteArray(),
  byteOut.size(),
  gamerToSend.getInetAddress(),
  3887
);

this.socket.send(packet);

byteOut.close();
out.close();

INetAddress info: (Ip is correctly displaying destination machine)

address Inet4Address    /192.168.0.101  /192.168.0.101  
Static      
INADDRSZ    int 4   4   
serialVersionUID    long    3286316764910316507 3286316764910316507 
loopback    int 2130706433  2130706433  
IPv4    int 1   1   
IPv6    int 2   2   
preferIPv6Address   boolean false   false   
nameService InetAddress$1   java.net.InetAddress$1@5bf0cf51 java.net.InetAddress$1@5bf0cf51 
serialVersionUID    long    3286316764910316507 3286316764910316507 
addressCache    InetAddress$Cache   java.net.InetAddress$Cache@1ebafdff java.net.InetAddress$Cache@1ebafdff 
negativeCache   InetAddress$Cache   java.net.InetAddress$Cache@679801c  java.net.InetAddress$Cache@679801c  
addressCacheInit    boolean true    true    
unknown_array   InetAddress[]   #1266(length=1) #1266(length=1) 
impl    Inet6AddressImpl    java.net.Inet6AddressImpl@12c9b196  java.net.Inet6AddressImpl@12c9b196  
lookupTable HashMap "size = 0"  "size = 0"  
$assertionsDisabled boolean true    true    
Inherited               
hostName                
address int -1062731675 -1062731675 
family  int 2   2   
canonicalHostName               
caport  int 3889    3889    

Server source
http://pastebin.com/JCdjhFQM

Answer 1

thanks for your help.

It appears the InetAddress is corrupted somewhere as manually setting it to the remote machine like so:

InetAddress addr = InetAddress.getByName("192.168.0.101");

Works perfectly fine, so I have more debugging to do, but thats the problem.

Again thanks for the assist!