What does -1 from DataInputStream's read() mean?

Question

According to Java documentation, the read() method returns:

• -1 if there is no more data because the end the stream has been reached

I don't quite understand what they mean by "end of stream".

Currently I close/re-open the socket when this occurs (which I understood from much Googling to be an acceptable way to deal with this). Is -1 possibly "normal" behavior? Should I not react so dramatically? Perhaps it would be better to only get upset on an IOException?

Socket creation:

clientSocket = new Socket(InetAddress.getByName(remoteHost), remotePort, InetAddress.getByName(sourceIpAddress), 0);

Some background information:

• i am using the 'localAddr' attribute when creating the socket (project requirement)
• i am running under Windows XP SP2
• i have no idea how the remote server is handling sockets (or even what language, not that that should matter)
• this occurs very rarely (perhaps once a day)
• only happens with one specific remote client running Linux
• the trouble-some client and myself are both behind numerous firewalls
• this never occurs with clients running various flavors of XP (perhaps it's time to setup a VMware image running Linux!)

Answer 1

The other end of the socket has closed the stream, so there is no more data to read - you've reached the end. I'd diagnose further with a network monitor such as Wireshark as to why the socket gets closed.