Book Image

Android Programming for Beginners

By : John Horton, Paresh Mayani
Book Image

Android Programming for Beginners

By: John Horton, Paresh Mayani

Overview of this book

Android is the most popular OS in the world. There are millions of devices accessing tens of thousands of applications. It is many people's entry point into the world of technology; it is an operating system for everyone. Despite this, the entry-fee to actually make Android applications is usually a computer science degree, or five years’ worth of Java experience. Android Programming for Beginners will be your companion to create Android applications from scratch—whether you’re looking to start your programming career, make an application for work, be reintroduced to mobile development, or are just looking to program for fun. We will introduce you to all the fundamental concepts of programming in an Android context, from the Java basics to working with the Android API. All examples 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, make location-aware apps with Google Maps integration, and store your user’s data with SQLite. In addition, you’ll see how to make your apps multilingual, capture images from a device’s camera, 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 (37 chapters)
Android Programming for Beginners
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Polymorphism


We already know that polymorphism means different forms. But what does it mean to us?

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

This means we can write code that is simpler and easier to understand and also easier to modify or change.

Also, we can write code for the super class and rely on the fact that no matter how many times it is subclassed, within certain parameters, the code will still work.

Let's discuss an example.

Suppose we want to use polymorphism to help write a zoo management app. We will probably want to have a method like feed. We will also probably want to pass a reference to the animal to be fed into the feed method. This might seem like we need to write a feed method for each and every type of Animal.

However, we can write polymorphic methods with polymorphic return types and arguments:

Animal feed(Animal animalToFeed){
  // Feed any animal here
  return animalToFeed;
}

The preceding...