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

Arrays and ArrayLists are polymorphic


We already know that we can put objects into arrays and ArrayList. But being polymorphic means they can handle objects of multiple distinct types as long as they have a common parent type all within the same array or ArrayList.

In Chapter 10, Object-Oriented programming, we learned that polymorphism means different forms. But what does it mean to us in the context of arrays and ArrayList?

Boiled down to its simplest form: any subclass can be used as part of the code that uses the super class.

For example, if we have an array of Animals, we could put any object that is a type that is a subclass of Animal in the Animal array—for example, Cats and Dogs.

This means we can write code that is simpler and easier to understand, as well as easier to change:

// This code assumes we have an Animal class
// And we have a Cat and Dog class that extends Animal
Animal myAnimal =  new Animal();
Dog myDog = new Dog();
Cat myCat = new Cat();
Animal [] myAnimals = new Animal...