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

All the Android UI elements are classes too


When our app is run and the setContentView method is called from onCreate, the layout is inflated from XML UI classes and loaded into memory as usable objects. They are stored in a part of the DVM's memory, called the Heap.

Re-introducing references

But where are all these UI objects/classes? We certainly can't see them in our code. And how on earth do we get our hands on them?

The DVM inside every Android device takes care of memory allocation to our apps. In addition, it stores different types of variables in different places.

Variables that we declare and initialize in methods are stored on an area of memory known as the Stack. We can stick to our existing warehouse analogy when talking about the Stack – almost. We already know how we can manipulate variables on the Stack with straightforward expressions. So, let's talk about the Heap and what is stored there.

Note

Important fact: All objects of classes are reference type variables and are just...