Question

I’m developing an Android 3.1 Tablet application that runs a service with this thread:

public class UDPServerThread extends Thread
{
    [ ... ]

    public void run()
    {
        while (!end)
        {
            try
            {
                byte[] buf = new byte[MESSAGE_SIZE];

                // Wait an incoming message.
                DatagramPacket packet = new DatagramPacket(buf, buf.length);
                socket.receive(packet);
                // TODO: Notify Service with packet received
                Message msg = new Message();
                msg.obj = packet;
                mServiceHandler.sendMessage(msg);
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }
    }

    public void stopServer()
    {
        Log.v("UDPServerThread", "stopServer");
        if (socket != null)
            socket.close();
        end = true;
    }
}

When I call stopServer() method from service I get the following error:

java.net.SocketException: Interrupted system call

Which is the right way to stop this thread while it is on socket.receive(packet);?

Answer 1

The only real problem with this exception is that you cannot easily distinguish it from an actual I/O error. I’d suggest switching to using a SocketChannel rather than a Socket — then you can interrupt your server thread and it will throw a ClosedByInterruptException instead, which you can catch and handle specifically.