onPause

onPause is a lifecycle callback in Android development, used by components such as Activity and Fragment. It is invoked when the component is about to lose foreground focus, typically because another activity is starting, the user navigates away to another app, or the device screen turns off. In multi-window or picture-in-picture scenarios, onPause may be called while the component remains visible but not in focus.

The primary purpose of onPause is to prepare for the transition away from the foreground. After onPause, the system may call onStop if the activity or fragment is no longer visible. It is not guaranteed to be invoked in all situations, such as when the system kills the process. Because onPause runs while the app is still visible or partially obscured, it should complete quickly and not perform long-running tasks.

Common uses include releasing exclusive resources (for example, the camera, microphone, or sensors), pausing animations or video playback, unregistering broadcast receivers, and persisting unsaved user data or preferences. These actions help conserve battery, prevent resource conflicts, and preserve the user’s progress.

In the lifecycle flow, onResume is called when the user returns to the component, allowing it to reinitialize resources and restore state. For fragments, onPause serves a similar role and is invoked when the hosting activity pauses or the fragment stops interacting with the user.

Best practices emphasize quick, non-blocking work in onPause and delegating longer operations to background threads or later lifecycle methods, ensuring a smooth user experience during transitions.