CODEWITHSUNDEEP
android
Drew S
Drew S

Reputation: 357

Monitor every battery state change even with screen off

I want my app to monitor every percent change and be able to execute some code when it changes even when the screen is off.

Yes, I know this is a bad idea and will drain battery unnecessarily. I am giving the user the option to turn this off. Also, this is more of an experiment at this point than a user-friendly feature. So please do not answer that I should not monitor every change.

I also know this is possible because Tasker implements this quite well. You can set a profile to do something on "Battery Changed" and it works when the screen is off. How is Tasker doing this?

From my research I have found that I will probably need to use AlarmManager and a partial wake lock from the PowerManager class. However I don't know how to best use these classes. Should I set an alarm manager to check every minute for a change? Tasker seems to not eat up too much battery when doing this so I would like to keep that in mind.

I have this working when the screen is on just fine. I have a service that registers an ACTION_BATTERY_CHANGED intent filter and a receiver to implement my code that I want to run. However when the screen is off, the code does not run until I "wake" the device by turning on the screen.

Upvotes: 0

Views: 559

Answers (1)

CommonsWare
CommonsWare

Reputation: 1006944

How is Tasker doing this?

You would have to ask the developers of Tasker.

Should I set an alarm manager to check every minute for a change?

It would not need to be nearly that frequent. You can only get battery charge levels in integer percentages, at best. Checking every 5-10 minutes is probably more than sufficient. You could also consider:

  • Letting users control the polling frequency

  • Implementing a learning algorithm that tries to determine a good polling interval based upon how the device has behaved previously

I have a service that registers an ACTION_BATTERY_CHANGED intent filter and a receiver to implement my code that I want to run.

Yuck. There is no added value for you tying up memory waiting for the battery level to tick over.

You can get the current battery level by calling registerReceiver() with an IntentFilter for ACTION_BATTERY_CHANGED and a null BroadcastReceiver. registerReceiver() will return the last ACTION_BATTERY_CHANGED broadcast that went out. Hence, again, a polling mechanism should be just fine.

Upvotes: 1

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