When a project is created using the Fragment + ViewModel template, the structure of the project differs in a number of ways from the Basic Activity used when the AndroidSample project was created. The key components of the project are as follows:
The first point to note is that the user interface of the main activity has been structured so as to allow a single activity to act as a container for all of the screens that will eventually be needed for the completed app. The main user interface layout for the activity is contained within the app -> res -> layout -> main_activity.xml file and provides an empty container space in the form of a FrameLayout (highlighted in Figure 39-1) in which screen content will appear:
The FrameLayout container is just a placeholder which will be replaced at runtime by the content of the first screen that is to appear when the app launches...
