Book Image

Android Programming for Beginners - Second Edition

By : John Horton
Book Image

Android Programming for Beginners - Second Edition

By: John Horton

Overview of this book

Are you trying to start a career in programming, but haven't found the right way in? Do you have a great idea for an app, but don't know how to make it a reality? Or maybe you're just frustrated that in order to learn Android, you must know Java. If so, then this book is for you. This new and expanded second edition of Android Programming for Beginners will be your companion to create Android Pie applications from scratch. We will introduce you to all the fundamental concepts of programming in an Android context, from the basics of Java to working with the Android API. All examples use the up-to-date API classes, and are created from within Android Studio, the official Android development environment that helps supercharge your application development process. After this crash course, we'll dive deeper into Android programming and you'll learn how to create applications with a professional-standard UI through fragments and store your user's data with SQLite. In addition, you'll see how to make your apps multilingual, draw to the screen with a finger, and work with graphics, sound, and animations too. By the end of this book, you'll be ready to start building your own custom applications in Android and Java.
Table of Contents (35 chapters)
Android Programming for Beginners - Second Edition
Contributors
Preface
Other Books You May Enjoy
Index

The structure of Java code – revisited


We have already seen that each time we create a new Android project, we also create a new Java package as a kind of container for the code we write.

We have also learned about and played around with classes. We have imported and taken direct advantage of classes from the Android API, such as Log and Toast. We have also used the AppCompatActivity class, but in a different manner to that of Log and Toast. You might recall that the first line of code in all our projects so far, after the import statements, used the extends keyword:

public class MainActivity extends AppCompatActivity {

When we extend a class, as opposed to just importing it, we are making it our own. In fact, if you take another look at the line of code, you can see that we are making a new class with a new name, MainActivity, but basing it on the AppCompatActivity class from the Android API.

Note

AppCompatActivity is a slightly modified version of Activity. It gives extra features to older...