CODEWITHSUNDEEP
androidsocketsgoogle-glassgoogle-gdk
Tyler Helmuth
Tyler Helmuth

Reputation: 129

EADDRINUSE When creating server socket on google glass

I am developing a google glass/android application. It is a video streaming application that has a server/client setup where the phone/glasses is the server and hooks the pc up with the session description for playing the video. It works great on the android and everything runs fine but as soon as I try to test it on the google glass it throws an error at this line 

sSocket = new ServerSocket(sPort);

The exception message says "EADDRINUSE" which I'm assuming means the port is already opened but I never opened it. Even if I had opened it and my program didn't close it I changed the port a couple of times and it still says it's in use.

Thanks

Upvotes: 1

Views: 249

Answers (1)

Devarsh Desai
Devarsh Desai

Reputation: 6112

Tyler,

Google Glass, like android, consistently will have many of it's ports occupied by applications running in the background. When creating a socket for your server to listen on, you have two choices:

1) Have a predetermined list of ports you can choose to have your server listen on.

If you choose to do this, then you can simply have a datastructure (list, queue, heap [if you have some priority of which ports you would like to use], etc) which contain all of your ports, then you can simply traverse them until you find an open port.

This can be achieved in the following manner:

private ServerSocket allocatePort(List<Integer> myArray) throws IOException {
    for (int individualPort : myArray) {
        try {
            return new ServerSocket(individualPort);
        } catch (IOException io) {
            continue; // An exception will be thrown if this port is currently in use. It's OK, let's try another port.
        }
    }

    // When no ports are available, let's throw an exception stating we were unable to find an open port.
    throw new IOException("we were unable to find an open port");
}

Then simply invoke this method within your as follows:

int[] arrayOfPorts = {5000, 5001, 5002, 8000, 8001, 8002, 8003};
List<Integer> myArray = new ArrayList<>();
myArray = IntStream.of(arrayOfPorts).boxed().collect(Collectors.toList());
ServerSocket sSocket = allocatePort(myArray);

2) If you don't mind which port to listen in on, you can use the constructor to pick any available port.

This can be achieved as follows:

  ServerSocket sSocket = new ServerSocket(0);

You can read up more on ServerSocket's Javadocs. Notice under the parameter's subsection:

  port - the port number, or 0 to use a port number that is automatically allocated.

Please let me know if you have any questions!

Upvotes: 1

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