Now that you have a basic app, it’s time to add some more features. To start, you’ll need to handle some more events from the user, create an ongoing notification, and list extra options in a menu. Along the way, you’ll learn the specifics of supporting multiple device configurations; explore event callbacks and multiple event filtering; create notifications, toasts, and dialogs to alert the user; and learn when and how to create menus.
Android is designed to operate on a wide range of hardware devices, but writing a separate interface for every device would be a nightmare. Luckily, the Android OS provides a number of abstractions that support this diverse set of hardware.