onStop

onStop is a callback in the Android Activity lifecycle. It is invoked when the activity is no longer visible to the user. It occurs after onPause, typically when another activity comes to the foreground or the user navigates away from the app, or when the activity is finishing. The system may keep the activity instance in memory after onStop, allowing a quick return if the user navigates back.

The main purpose of onStop is to release or suspend resources that are not needed while the activity is invisible, such as stopping animations, halting location updates, or releasing heavy resources like the camera or sensors. It is also a suitable place to commit UI changes or small state saves, though more critical state should be saved in onPause or onSaveInstanceState.

If the user returns to the activity, onRestart and onStart (and onResume) may be called to bring it back to the foreground. If the activity is finishing, onDestroy will follow after onStop.

Note that onStop is not guaranteed to be called in every situation. If the process hosting the app is killed by the system, onStop (and other lifecycle callbacks) may be skipped. Therefore, critical data should be saved in onPause and in onSaveInstanceState to ensure restoration.