43.3 Identifying and Preparing the Root Container
When working with transitions it is important to identify the root container for the scenes. This is essentially the parent layout container into which the scenes are going to be displayed. When the project was created, Android Studio created a layout resource file in the app -> res -> layout folder named activity_main.xml and containing a single layout container and TextView. When the application is launched, this is the first layout that will be displayed to the user on the device screen.
Begin by locating the activity_main.xml layout resource file, loading it into the Android Studio Layout Editor tool and deleting the default TextView widget. Select the ConstraintLayout entry within the Component Tree window and change the ID property in the Attributes tool window to rootContainer.