how to callback into various activities from a android library

Question

I've written a library for Android, upon initialising the library I register for call backs for location updates, subscription status changes, library status changes and various other updates... Originally, I wanted all these updates to call back to a controller in my android UI app, and then for the controller to launch activity A, pass on the messages from the controller to activity A and so on. Or launch activity B for signing up for a subscription and forward messages to this etc However, it appears that there isn't a way to achieve this - Because each activity is in isolation? Unless I'm mistaken?

So what are my options here? It sounds like I either have to use one activity for the whole app and swap the UI's which after looking into it doesn't appear to be the way to go?

I did try to subclass Application, which worked and gave me access to my library from an activity – but I want it the other way around. Is this possible? would wrapping the library in a service achieve what I want to do?

Answer 1

You could use broadcasts and send them from your library. Each of your activities would have to register a BroadcastReceiver in their onResume() method and unregister it in their onPause() method. This would be comparatively easy when you use a common base class for your activities. You could then send commands from your library to whatever activity is currently active.