Question

I have a thread running in my Swing chat application to listen indefinitely through a socket for datagrams. When I close this application, I have the following code execute:

listenThread.interrupt();
socket.close();

However, interrupt doesn’t seem to be stopping the thread, as when the socket closes, the loop continues listening, and throws exceptions since the socket has been closed. How do I get the thread to exit properly so that I can close the socket safely?

Answer 1

interrupt() cannot be used to interrupt an I/O operation such as socket reads or writes. To abort the I/O, closing the socket is the right way. After your thread receives the IOException it should check if it was interrupted in the meantime and then gracefully exit.

Example for the code in your I/O thread:

while( !Thread.currentThread().isInterrupted() ) {
  try {
    doRead();
  } catch ( IOException ioe ) {
    // Log exception or whatever
  }
}