Question

I’m using naga to do some asynchronous socket programming.

However I need to be able to attach arbitrary data to the Socket objects.

For instance I have code like so:

service = new NIOService();
// Server is JSONObject
NIOSocket socket = service.openSocket(Server.getString("ip"), Server.getInt("port"));
??? Add mydata to socket
socket.listen(observer); // See class below
System.out.println(socket.mydata);// get new data


public static class Observer extends SocketObserverAdapter {

        //Called when Socket makes connection
        @Override
        public void connectionOpened(NIOSocket socket) {
            System.out.println(socket.mydata); // get data
            socket.mydata = "yay!";// set data
        }
}

The problem I have is that I need to both get and set data on a socket object in the Observer.connectionOpened callback, and be able to access it later.

I realize that there probably isn’t a way to just add data to the object, but what’s the best way to associate data with the object so that I can pass it around and still access (and modify) the data?

I can always recompile the class code to add the variables to the class, but that seems very hackish, which I try to stay away from.

Note: I’m fairly new to Java programming, but not to programming in general.

Answer 1

The two approaches that come to mind are:

Wrap the Socket in a class that carries information around

class MySocketWithData {
    private final Socket theSocket;
    private String myData;
    ....
}

or, Maintain a Map that holds the information you care about.

private final Map<Socket, MyCoolData> socketMap = new ConcurrentHashMap<>();
public void doSomething(Socket sock) {
    MyCoolData data = socketMap.get(sock);
}

I’d probably prefer the first. The second would be more appropriate if you need to hand Socket instances around themselves and can’t substitute your own class.