How does ViewModel maintain its viability after the Activity is destroyed?

The ViewModel in Android preserves its viability after the Activity is destroyed because it is tied to the component's lifecycle at the architecture level, not directly to the Activity.

When an Activity is destroyed, for example, during a screen rotation, the system creates a new Activity, but the ViewModel persists and is provided to the new Activity of the same lifecycle.

This is achieved using the ViewModelProvider class, which stores an instance of the ViewModel in a special storage associated with the lifecycle of the owner (Activity or Fragment). As long as the owner is alive, the ViewModel is preserved.

Thus, ViewModel allows maintaining state and data across Activity recreations without the need to manually save them via onSaveInstanceState.

Example:

val viewModel = ViewModelProvider(this).get(MyViewModel::class.java)

Here, this is an Activity or Fragment, and the ViewModel will live as long as this component is alive, even if the Activity is recreated.