Final answer:
Android doesn't always save the data of an activity by default, but you can use methods like on Save Instance State() or Shared Preferences to save and restore the data.
Step-by-step explanation:
Android doesn't always save the data of an activity when you navigate away from it or close the app. This is because Android follows a specific lifecycle for activities, which includes different stages like on Create(), on Resume(), on Pause(), and on Destroy(). When an activity is paused or destroyed, the data associated with that activity is not automatically saved by default. To save the data of an activity, you can use methods like on Save Instance State() or Shared Preferences. on Save Instance State() allows you to save key-value pairs of data that will be restored when the activity is recreated. Shared Preferences, on the other hand, allows you to save data in a persistent storage that can be accessed even after the app is closed and reopened.
For example, if you have an activity with a counter, you can save the counter value in on Save Instance State() and restore it in on Create(). This way, when you navigate away from the activity and return to it, the counter value will be preserved.