Your GeoQuiz application will consist of an activity and a layout:
An activity is an instance of Activity, a class in the Android SDK. An activity is responsible for managing user interaction with a screen of information.
You write subclasses of Activity to implement the functionality that your app requires. A simple application may need only one subclass; a complex application can have many.
GeoQuiz is a simple app and will start off with a single Activity subclass named MainActivity. MainActivity will manage the user interface, or UI, shown in Figure 1.1.
A layout defines a set of UI objects and the objects’ positions on the screen. A layout is made up of definitions written in XML. Each definition is used ...