What is the reason for having the onCreate method in the Application class and the absence of the onDestroy method?

The onCreate() method in the Application class is called once when the application starts and is used to initialize global resources and settings that should be accessible throughout the application.

The absence of the onDestroy() method is related to the fact that the lifecycle of the Application object is not directly managed by the system, and the application can be terminated without calling any cleanup method. Android may kill the application process at any time to free resources, without calling onDestroy().

Therefore, it is recommended to use other components (such as Activity or Service) for resource cleanup and state preservation, where lifecycle methods are more predictable, or to use mechanisms like onTrimMemory() or onLowMemory() in Application to respond to system events.