Exercises

1.4 Fill in the blanks in each of the following statements:

a) Android apps are developed with _____________—one of the world’s most widely used programming language, a logical choice because it’s powerful, free and open source.

b) GUI programming in Java is _____________ driven, you’ll write apps that respond to various user interactions such as screen touches and keystrokes.

c) Touching the screen and holding your finger in position is called a _____________.

d) Touching the screen, then moving your finger in one direction and releasing it is called a _____________.

e) Before running an app in the emulator, you'll need to create an _____________, which defines the characteristics of the device on which you want to test, including the hardware, system image, screen size, data storage and more.

f) Performing a task in a program requires a _____________ which houses the program statements that actually perform its tasks.

g) You must build an object of a class before a program can perform the tasks that the class’s methods define. The process of doing this is called _____________.

h) _____________ helps you build more reliable and effective systems, because existing classes and components often have gone through extensive testing, debugging and performance tuning.

i) Classes _____________ (i.e., wrap) attributes and methods into objects—an object’s attributes and methods are intimately related.

j) A new class of objects can be created quickly and conveniently by _____________—the new class absorbs the characteristics of an existing one, possibly customizing them and adding unique characteristics of its own.

k) Unlike actual buttons on a device, _____________ buttons appear on the device’s touch screen.

l) Colors are defined using the RGBA color scheme in which the red, green, blue and _____________ components are specified by integers in the range 0–255.

1.5 State whether each of the following is true or false. If false, explain why.

a) The vast majority of Android development is done in C++.

b) Microsoft Visual Studio is the recommended integrated development environment for Android development, though developers may also use a text editor and command-line tools to create Android apps.

c) You can reproduce on the emulator most of the Android gestures and controls using your computer’s keyboard and mouse.

d) Objects, or more precisely the classes objects come from, are essentially reusable software components.

1.6 One of the most common objects is a wrist watch. Discuss how each of the following terms and concepts applies to the notion of a watch: object, attributes, behaviors, class, inheritance (consider, for example, an alarm clock), messages, encapsulation and information hiding.