CODEWITHSUNDEEP
androidonpauseondestroy
committedandroider
committedandroider

Reputation: 9261

How can we guarantee that onPause will be called?

Going of this question android save game state in onPause or onDestroy?

The answer highlighted that the person asking the question should save game state in onPause because the onDestroy documentation says "There are situations where the system will simply kill the activity's hosting process without calling this method (or any others) in it, so it should not be used to do things that are intended to remain around after the process goes away." In these situations, how can we ensure onPause will be called? Is it possible to control what methods are called in these situations? Seems unpredictable

Upvotes: 0

Views: 122

Answers (4)

Squonk
Squonk

Reputation: 48871

It's almost certain that onPause() will always be called. The reasoning is that it's highly unlikely the "system" will aggressively kill an active (i.e., visible) Activity.

In order to free resources, the Android OS effectively reserves the right to kill dormant processes - in particular ones that have been long-running but not recently used. In order for your Activity (and its process) to qualify for this, at some point you must have sent the Activity to a background state, e.g., pressed HOME or started another app's Activity. The simple fact your Activity is no longer visible means it will have been paused and onPause() will have been called. It's almost certain that the Activity will have been stopped and onStop() will have also been called.

What you have to remember is Android has been around for a while now and early devices had RAM measured in 100s of MB and the system behaviour possibilities and documentation reflects this. More recent devices have RAM measured in GB (even 10s of GB) so unless a user really pushes their device to the limitations of its resources, aggressive clean-up of app processes becomes less likely.

Upvotes: 0

Code-Apprentice
Code-Apprentice

Reputation: 83537

You should save temporary instance state in onSaveInstanceState(). This method recieves a Bundle parameter which you can use to write state to. The Bundle is then sent to onCreate() when your app is restarted.

If you need to save instance state more permanently, then save it to a database or SharedPreferences. According to http://developer.android.com/training/basics/activity-lifecycle/stopping.html, you should use onStop() for more CPU-intensive operations rather than onPause(). I don't think you need to worry about onPause() being called in normal use cases. As far as I can tell, it is guaranteed. (Of course, there are always catastrophic failures, such as the user pulling out the battery of the device, but there's not much you can do about that.)

Upvotes: 2

Janusz
Janusz

Reputation: 189484

onPause will be called every time your activity leaves the screen, before it is finished or if something overlays your activity that keeps the user from interacting with your activity.

You don't need to worry that onPause is not called.

For more information look into the starting and stopping activity training or the Lifecycle Api Docs

Upvotes: 2

DeepakPanwar
DeepakPanwar

Reputation: 1389

You can show Dialog for User to Act Accordingly.When Dialog will be opened to ask user that he wants to quit or not,Activity will definitely call onPause() and at this time you can write your game state saving code. Its better to write code on onPause() because at onDestroy() resources are freed by os.

Upvotes: -3

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