Prompt Title: Activity life cycle

Android Activity is a fundamental component of an Android application that represents a single screen with a user interface. The activity lifecycle is a series of events that an activity goes through during its lifetime. Understanding the activity lifecycle is essential for developing robust and responsive Android applications.

The activity lifecycle consists of four states:

1. Active/Running State - The activity is in the foreground, and the user can interact with it.

2. Paused State - The activity is partially visible, and another activity has gained focus. The paused state indicates that the activity is still visible to the user but is not in the foreground.

3. Stopped State - The activity is completely hidden, and the system may have killed it to free up resources. In the stopped state, the activity is not visible to the user, and its resources may be released by the system.

4. Destroyed State - The activity is finished or killed by the system or user. Once the activity is destroyed, it cannot be resumed or restarted.

The activity lifecycle events are methods that are called when an activity transitions from one state to another. Here are the events that are called during different states:

1. onCreate() - This method is called when the activity is created for the first time.

2. onStart() - This method is called when the activity becomes visible to the user.

3. onResume() - This method is called when the activity is in the foreground and the user can interact with it.

4. onPause() - This method is called when the activity loses focus but is still visible to the user.

5. onStop() - This method is called when the activity is no longer visible to the user.

6. onRestart() - This method is called when the activity is stopped and then started again.

7. onDestroy() - This method is called when the activity is about to be destroyed.

By understanding the activity lifecycle and the events that are called during different states, you can write better Android applications that provide a better user experience and handle the state changes gracefully.