Book Image

Learning Java by Building Android Games - Second Edition

By : John Horton
Book Image

Learning Java by Building Android Games - Second Edition

By: John Horton

Overview of this book

Android is one of the most popular mobile operating systems presently. It uses the most popular programming language, Java, as the primary language for building apps of all types. However, this book is unlike other Android books in that it doesn’t assume that you already have Java proficiency. This new and expanded second edition of Learning Java by Building Android Games shows you how to start building Android games from scratch. The difficulty level will grow steadily as you explore key Java topics, such as variables, loops, methods, object oriented programming, and design patterns, including code and examples that are written for Java 9 and Android P. At each stage, you will put what you’ve learned into practice by developing a game. You will build games such as Minesweeper, Retro Pong, Bullet Hell, and Classic Snake and Scrolling Shooter games. In the later chapters, you will create a time-trial, open-world platform game. By the end of the book, you will not only have grasped Java and Android but will also have developed six cool games for the Android platform.
Table of Contents (30 chapters)
Learning Java by Building Android Games Second Edition
Contributors
Preface
Index

Polymorphism


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

Boiled down to its simplest:

Note

Any subclass can be used as part of the code that uses the superclass.

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

Also, we can write code for the superclass and rely on the fact that no matter how many times it is sub-classed, within certain parameters, the code will still work. Let's discuss an example.

Supposing we want to use polymorphism to help write a zoo management game. We will probably want to have a method like feed. We will 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 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 method above has an Animal as a parameter...