Many Android devices incorporate touch screens. When a device does not have a physical keyboard, much of the user input
come through the touch screen. Therefore your applications will often need to be able to deal with touch input from the user. You’ve most likely already seen the virtual keyboard that displays on the screen when text input is required from the user. We used touch with mapping applications in Chapter 17 to pan the maps sideways. The implementations of the touch screen interface have been hidden from you so far, but now we’ll show you how to take advantage of the touch screen.