CODEWITHSUNDEEP
androidandroid-broadcastreceiver
bvk256
bvk256

Reputation: 1903

BroadcastReceiver persistent during the whole activity lifecycle

I have an application that makes async HTTP requests from various places (app activities and a background service). I'd like to catch response events inside my main activity and modify some views. This is achieved by using anonymous class BroadcastReceiver inside the main activity. The registering/unregistering of the broadcast receiver is inside onResume()/onPause().

The problem is that when screen is off and the activity is not in the foreground the events aren't caught, because the receiver is unregistered. How to catch all events even in background while preserving register/unregister coherency of BroadcastReceiver?

Upvotes: 0

Views: 681

Answers (3)

bvk256
bvk256

Reputation: 1903

I solved the problem by adding EventBus lib. The handler is implemented inside the main activity, activity subscribes for events on onCreate() and unsubscribes on onDestroy(). Since EventBus lib is built on standard Java components I expect the garbage collector to automatically clean up everything even if onDestroy() is not called.

Futhermore I used WeakReference for my views which allows to check if an activity is already disposed to prevent unexpected errors.

This may be not the best solution, but it works for now and much easier to implement than other proposed answers.

Upvotes: 0

Dzhuneyt
Dzhuneyt

Reputation: 8701

Your best bet here would be to start a persistent background service (with a local broadcast receiver).

Here are some starting points:

  • Your service's onStartCommand() should return START_STICKY, so it's not killed by the OS.
  • You should create a local variable inside the Service that holds your broadcast receiver and register this receiver in onStart() and unregister it in onDestroy().
  • Start the service whenever you find suitable (e.g. onCreate() of the Application, since it's only called once per application life-cycle and is not tied to a specific Activity).

This answer might help.

Your existing approach doesn't work because when the screen is turned off, the onPause signal is sent to all your activities and they automatically unregister the local broadcast receiver (and they should be).

Upvotes: 2

Sachin Kukreja
Sachin Kukreja

Reputation: 107

There two alternatives

  1. Have a service running and register the receiver there instead.

  2. You can register the broadcast receiver in the manifest and handle it there. Please keep in mind that the receiver will run on the main thread, so you should signal to a running service perhaps a service that performs a single task.

A service that performs a single task can be implemented using IntentService. It is kind of like an async task wrapped in a service.

Upvotes: 1

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