21.3 Overriding the Activity Lifecycle Methods

At this point, the project contains a single activity named MainActivity, which is derived from the Android AppCompatActivity class. The source code for this activity is contained within the MainActivity.kt file which should already be open in an editor session and represented by a tab in the editor tab bar. In the event that the file is no longer open, navigate to it in the Project tool window panel (app -> java -> com.ebookfrenzy.statechange -> MainActivity) and double-click on it to load the file into the editor.

So far the only lifecycle method overridden by the activity is the onCreate() method which has been implemented to call the super class instance of the method before setting up the user interface for the activity. We will now modify this method so that it outputs a diagnostic message in the Android Studio Logcat panel each time it executes. For this, we will use the Log class, which requires that we import android...