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 other interfaces


There are three more interfaces that we need to code. They are for communications between specific classes of the game. We need the GameState class to be able to trigger a new level via the GameEngine class and we will code the EngineController interface for that.

We will need the GameEngine class to broadcast to multiple input related classes whenever the player interacts with the screen and we will need these input-related classes to register themselves as observers just as we did in the previous project. For this we will code the GameEngineBroadcaster interface and the InputObserver interface.

Let's quickly add them now.

EngineController

Add the EngineController interface as shown next.

interface EngineController {
    // This allows the GameState class to start a new level
    void startNewLevel();
}

In the next chapter we will make GameEngine implement this interface as well as pass a reference to GameState. GameState will then be able to call the startNewLevel...