Question

I’ve got a little gap in my knowledge here and I want to make sure I do it right before writing all the wrong code.

I have an Android app that extends Application to set up some core functions for a TCP client. There are a few different Activity screens that should interact with Application. What I’m stuck on, is what to do when a data packet is received by Application. I want to relay it to the currently-visible Activity, whatever it is.

Coming from a C# background, I’d just create an Event in the Application, and simply subscribe to that event when an Activity is created. But I’m getting confused with Java Listeners, Handlers, …

What’s the best way to go about that? Should I be doing a Service instead? (But I don’t really care if the TCP connection is killed when the app is not shown.)

Answer 1

I would go with a LocalBroadcastManager (documentation) approach.

Create one of those puppies in your Application class, and register/unregister your Activity objects in onStart and onStop. See Context.registerReceiver. Note that this requires using Intents, which might be too restrictive/heavy-weight for your application; packing/unpacking data can be a chore.

Alternatively, you don’t have to use any specific android class to do it–just keep track of what Activity your program is in by calls to your Application in onStart and onStop. Might help clean your code if you make all of your activities-of-interest extend a subclass of Activity that contains this logic.