Rotation

This projects demonstrates a strange behavior of the Android Activity lifecycle.

The Example App

This example app is set up with ParentActivity and ChildActivity. ParentActivity has one button that launches ChildActivity. ChildActivity has a transparent background so that ParentActivity isn't stopped when ChildActivity starts. Both Activities are otherwise very vanilla.

The Problem

When orientation change occurs after ChildActivity has been launched, locking the device results in only ChildActivity.onStop() being called, but not ParentActivity.onStop(). If no orientation change has occured, then both ChildActivity.onStop() and ParentActivity.onStop() are called when the device is locked.

Normal Behavior

1. ParentActivity.onStart()
2. Launch Child
3. ChildActivity.onStart()
4. Lock the screen.
5. ChildActivity.onStop()
6. ParentActivity.onStop()

Weird Behavior

1. ParentActivity.onStart()
2. Launch Child
3. ChildActivity.onStart()
4. Rotate the screen
5. ChildActivity.onStop()
6. ChildActivity.onStart()
7. ParentActivity.onStop()
8. ParentActivity.onStart()
9. Lock screen
10. ChildActivity.onStop()