How to distribute events among all activities?

Question

Java

I inherit from the Application class and create a DeviceProtocol class variable there.
DeviceProtocol is responsible for connecting to the device via BLE, because inside there are methods that require activation, then I pass this to it from SplashScreen (for this reason, I have to not destroy SplashScreen)
Next, I need to somehow make events, for example, onBatLevelUpdate, to which a bunch of other activities should subscribe.
That's actually the question, t .to. googling "android event" returns only element events

Answer 1

Reactive programming?
RxJava, RxAndroid to the rescue