Problem stopping Thread

[Brad Walton]

I am trying to stop a thread which listens for incoming socket data.

// Listens for server console output as new thread
public static class Listen implements Runnable
{
private volatile boolean stop;

// Exit the Listen thread
  public void stop()
  {
  stop = true;
  }

// Start the Listen thread
public void run()
{
while(!stop)
{
try
{
System.out.println("Server Reply: " + in.readLine());
}
catch (IOException ioe)
{
System.err.println("Listen: Couldn't get I/O for the connection!");
System.err.println(ioe.toString());
}
}
}
}

public static void main(String args[])
{
// Temp variables for testing - will be defined by config
String ipAddress = "192.168.1.55";
int port = 2001;

ServerConnection.connect(ipAddress, port); // connect to server

 // Start Listen thread
ServerConnection.Listen oListen = new ServerConnection.Listen();
new Thread(oListen).start();

// User input
String command = null;
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));

while(true)
{
try
{
command=stdin.readLine();
if (command.equals("stop")) break;
else ServerConnection.sendCommand(command);
}
catch (IOException ioe)
{
System.err.println("main: IO Error on user input!");
System.err.println(ioe.toString());
}
}
 
// Stop Listen thread
oListen.stop();

// Close connection to server
ServerConnection.disconnect();
}

When doing this, I get the an IO exception when closing the sockets, even though closing them is done after stopping this thread.

Listen: Couldn't get I/O for the connection!
java.net.SocketException: socket closed

Any ideas why this is happening? I thought the stop method would exit gracefully from the thread...

Thanks,
Sammie

[Henry Wong]

Any ideas why this is happening? I thought the stop method would exit gracefully from the thread...

What is happening is ... the stop flag is only checked when the readline() method returns, which in this case, is caused by an exception thrown when the socket is closed.

What you need to do is, in your catch block, is check to see if the stop condition is true. If it is, then you need to ignore the exception, don't print out the exception, and cleanup and exit gracefully.

Henry

[Brad Walton]

Thanks Henry