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

Coding the Observer pattern in Scrolling Shooter


Now we are well versed on how the Observer pattern works and we have had a good look at the interfaces we will need to write and how they will be used we can put all the theory into action in the Scrolling Shooter project.

As the specific use for our broadcaster and observers is to handle the player's input we will code a class to handle the screen touches for the HUD. As a reminder, the GameEngine class will be a Broadcaster and two separate classes that handle user input will be Observers. As the HUD and the player's spaceship are very different things it makes sense for each of them to handle their own input.

We will code the UIController class which will be our first Observer (for the HUD play/pause button) in this section and later in the project we will code our second Observer to handle the spaceship controls.

Note

As we have learned, there is nothing stopping us adding more observers or even more broadcasters for different events if we...