Check if the socket is closed

[Faab234]

I want to check if the socket is closed; Currently I'm using this:


/**
* The thread's process.
* <p>The serverChannel listens for incoming connections, and accepts them.
* The timeout is set to 1 to prevent i/o blocking.
*/
public void run() {
while (serverRunning) {
try {
socket = serverChannel.accept();
socket.setSoTimeout(soTimeout);
socket.setTcpNoDelay(tcpNoDelay);
SessionData socketData = new SessionData(socket);
channelEvent.sessionCreated(socketData);
int id = getFreeId();
sockets[id] = socket;
SessionHandler socketHandler = new SessionHandler(id);
if (sockets[id].isConnected() == true) {
channelEvent.sessionOpened(socketHandler, socketData);
}

PrintWriter out = new PrintWriter(sockets[id].getOutputStream());
out.println("lol");
out.flush();
if(out.checkError()) {
System.out.println("Session Closed");
}




} catch (Exception e) {
e.fillInStackTrace();
}
}
}


Unfortunately, the code doesn't work, because it doesn't check if the socket is closed. Why?

[Trey]

Use the isClosed method in the Socket class. Keep in mind also that if you try to acquire an InputStream from a closed socket it will throw an IOException, so that could be used as an indicator as well.

[Faab234]

Use the isClosed method in the Socket class. Keep in mind also that if you try to acquire an InputStream from a closed socket it will throw an IOException, so that could be used as an indicator as well.

I thought the isClosed method will be not true if the socket is closed client-side. Right?

[Trey]

I thought the isClosed method will be not true if the socket is closed client-side. Right?

Well, if you closed it yourself then why would you need to check if it's closed? lol.

[Faab234]

Well, if you closed it yourself then why would you need to check if it's closed? lol.

So I can delete them for the array.

[Trey]

So I can delete them for the array.

Remove them after you close them then. I don't understand what you're saying. If you're closing the socket from the server you can just remove them from your array after you close it. If it's closed from the client, just check every so often if the sockets are still open and if not remove them from the array the same way.

[Faab234]

Remove them after you close them then. I don't understand what you're saying. If you're closing the socket from the server you can just remove them from your array after you close it. If it's closed from the client, just check every so often if the sockets are still open and if not remove them from the array the same way.

If the socket is closed (Server and Client Sided), I want to call a method.

[Trey]

If the socket is closed (Server and Client Sided), I want to call a method.

There's no event trigged that the socket has been closed necessarily, you'll just have to check whenever you attempt to use that socket for anything.

[Faab234]

There's no event trigged that the socket has been closed necessarily, you'll just have to check whenever you attempt to use that socket for anything.

Already do that:


PrintWriter out = new PrintWriter(sockets[id].getOutputStream());
out.println("lol");
out.flush();
if(out.checkError()) {
System.out.println("Session Closed");
}


But it don't work.

[Trey]

Already do that:


PrintWriter out = new PrintWriter(sockets[id].getOutputStream());
out.println("lol");
out.flush();
if(out.checkError()) {
System.out.println("Session Closed");
}


But it don't work.

I wouldn't use a PrintWriter in the first place, considering it writes everything as text rather than as raw bytes, which is more ideal in networking applications. OutputStream.write throws an exception if the stream is closed, just do it that way as intended. InputStream.read will return -1 if the stream is closed as well.

Plus, by the looks of your current set up, it seems to me that NIO would be much more appropriate. SocketChannel's read method also returns -1 if the stream is closed, so you could use that if you go with NIO.

[Faab234]

I wouldn't use a PrintWriter in the first place, considering it writes everything as text rather than as raw bytes, which is more ideal in networking applications. OutputStream.write throws an exception if the stream is closed, just do it that way as intended. InputStream.read will return -1 if the stream is closed as well.

Plus, by the looks of your current set up, it seems to me that NIO would be much more appropriate. SocketChannel's read method also returns -1 if the stream is closed, so you could use that if you go with NIO.

Thanks, I'll also look at NIO.

edit; Not working.

[Trey]

Thanks, I'll also look at NIO.

edit; Not working.

If the socket isn't open it will throw an exception, that's the easiest way to handle it. No reason to make it more complex than it is =P

[Faab234]

If the socket isn't open it will throw an exception, that's the easiest way to handle it. No reason to make it more complex than it is =P

I know, but my code will be not executed.