Android activity recreate itself

Question

My app normally works just fine, until I face a strange problem on specific device. There are 2 activities in App. After I start ActivityB inside of ActivityA, ActivityA starts

Answer 1

The Activity documentation (http://developer.android.com/reference/android/app/Activity.html) says the following about the lifecycle of a background activity:

A background activity (an activity that is not visible to the user and has been paused) is no longer critical, so the system may safely kill its process to reclaim memory for other foreground or visible processes. If its process needs to be killed, when the user navigates back to the activity (making it visible on the screen again), its onCreate(Bundle) method will be called with the savedInstanceState it had previously supplied in onSaveInstanceState(Bundle) so that it can restart itself in the same state as the user last left it.

In other words, ActivityA may or may not be destroyed by the operating system while ActivityB is active, so this situation has to be handled in the code. If ActivityA has been destroyed, onCreate(Bundle) will be called, when the user presses the back button in ActivityB.