Configuration Changes

Configuration Changes and Recreation

A configuration change (rotation, language, dark mode, font scale, a window resized in multi-window or on a foldable) can make loaded resources wrong, so by default the system destroys the activity and creates a new one. Rotating the emulator shows the sequence:

Rotating the emulator to landscapeShell

adb shell settings put system accelerometer_rotation 0
adb shell settings put system user_rotation 1

Output

09-24 18:36:56.428 D/BookNestLife( 9238): onPause
09-24 18:36:56.441 D/BookNestLife( 9238): onStop
09-24 18:36:56.444 D/BookNestLife( 9238): onSaveInstanceState
09-24 18:36:56.478 D/BookNestLife( 9238): onDestroy changing=true
09-24 18:36:56.584 D/BookNestLife( 9238): onCreate restored=true
09-24 18:36:56.611 D/BookNestLife( 9238): onStart
09-24 18:36:56.621 D/BookNestLife( 9238): onResume

isChangingConfigurations tells a rotation from a real finish, and the process ID stays 9238, so a ViewModel survives here, unlike after process death. LocalConfiguration now reports landscape, rememberSaveable kept 3 and remember restarted at 0. In short: remember survives neither event, a ViewModel survives rotation only, saved state survives both, and only Room 234 , DataStore 234 or files survive the user swiping the app away.

BookDetail after three taps, after process death, and after rotation

android:configChanges="orientation|screenSize" in the manifest suppresses recreation for the listed changes, and Compose 234 still recomposes with the new configuration, but Google calls it a last resort. Locking the orientation is no escape either: at target API 36 it is ignored on screens 600 dp wide and larger.

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