Activity LifeCycle in Android

The lifecycle of an Activity represents the various states that an Activity goes through during its lifetime. Understanding the Activity lifecycle is crucial for developing Android apps as it helps you manage and control how your app responds to different events and user interactions. The Android Activity lifecycle consists of several key methods that get called at different stages. Here is an overview of the main lifecycle methods:

1. onCreate(): This is the first method that gets called when an Activity is created. You typically use this method to perform one-time initialization, such as setting up user interface elements and initializing variables. You must call super.onCreate(savedInstanceState) to ensure proper initialization.
2. onStart(): This method is called when the Activity becomes visible to the user but is not yet in the foreground. You can perform tasks like registering broadcast receivers or preparing to start animations in this method.
3. onResume(): This method is called when the Activity is in the foreground and the user can interact with it. It’s a good place to start animations, acquire resources like the camera, and begin listening for user input.
4. onPause(): When the Activity loses focus but is still visible, onPause() is called. This is where you should release resources that are no longer needed, such as stopping animations or releasing the camera.
5. onStop(): This method is called when the Activity is no longer visible to the user. It’s a good place to release resources that should only be held when the Activity is in the foreground.
6. onRestart(): If the Activity is stopped and then restarted, onRestart() is called before onStart(). You can use it to perform any additional setup needed when the Activity is being restarted.
7. onDestroy(): When the Activity is about to be destroyed, either due to the user navigating away from it or the system needing to free up memory, onDestroy() is called. This is where you should release any remaining resources and perform cleanup.

There are two more methods related to handling state changes:

• onSaveInstanceState(Bundle savedInstanceState): This method is called before onPause() when the system may need to kill the Activity to reclaim resources. You can use it to save the Activity’s state and data in a Bundle so that it can be restored later.
• onRestoreInstanceState(Bundle savedInstanceState): This method is called after onStart() when the Activity is being recreated. It allows you to restore the previously saved state and data from the Bundle passed as an argument.

Understanding and properly implementing these lifecycle methods is essential for building responsive and well-behaved Android applications. Managing the lifecycle ensures that your app behaves correctly when users switch between different activities, rotate the device, or perform other actions that can affect the state of your app’s components.