Most readers will be familiar thoroughly with Android Lifecycle. However, it is always useful to review this as it is a super important thing, and there might be some readers who haven't had a chance to know it so well.
The Android Activity Lifecycle describes an order and conditions on which the special methods are called:
Developers have to override them so that their code can get called at the points in the lifecycle specific to an activity:
In the preceding figure (taken from https://developer.android.com/guide/components/activities/activity-lifecycle.html ...