Question

Going through some tutorials about sockets, I keep coming across code like that:

  while(true){ 
    socket.receive(packet); 
    String message = new String(packet.getData(),0,packet.getLength(), TEXT_ENCODING); 
    System.out.println(message); 
  }  

Question is: How is this loop left? Only via the catch, once receive() is done?

To be more precise, here’s what I’ve done:

while(true) {
        try {
            socket.receive(answer);
            resultString = new String(answer.getData(), 0, answer.getLength(), "ASCII");

            if (isMyIdentifier(resultString)) {
                gatewayIP =  answer.getAddress().getHostAddress();
                return true;
            } else {
                return false;
            }
        }
        catch (SocketTimeoutException e) {
            throw new GatewayNotReachableException();
        }
    }

But I keep coming up with a timeoutexception, although the read is correct. So I was wondering, if the exception is the ‘expected’ way to leave. Although I seriously doubt that… ANd the socket.receive(packet) is, where the exception is thrown.

Answer 1

In the code below there is a continuous while loop, which may seem a suitable implementation, however some servers have a tendency to keep listening, and handle the requests simultaneously.

This while loop will never exit!

while(true){ 
    socket.receive(packet); 
    String message = new String(packet.getData(),0,packet.getLength(), TEXT_ENCODING); 
    System.out.println(message); 
  }