Android Applications Life-cycle

An android application does not have a main() method. The class android.Activity contains all the life-cycle methods for an android application. The android application life-cycle methods contained in the android.Activity are called at appropriate times when an android application is started, suspended, restarted, closed, etc. Android applications run in their own Unix process and, hence, cannot affect other running applications, directly.

Running android applications can be in one of the following three states, at one time:

1. Active: The application is running and visible to the user.

2. Paused: The application is running but does not have the focus i.e. partly obscured.

3. Stopped: The application is running but is completely hidden from view.

Android Application Life-cycle Methods:

An android application is transitioned among above listed states by Android calling the below listed methods on the current Activity at the appropriate times:

void onCreate(Bundle savedInstanceState)

void onStart()

void onResume()

void onRestart()

void onPause()

void onStop()

void onDestroy()

onCreate() method is the first activity of any android application. This is the most important method in the lifecycle of an android application. This method acts like a constructor in an android application. Here we normally do our constructor like work. In fact onCreate() is the method that even the simplest of android application would need.