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

Using the HUD and Renderer classes


Declare an instance of the HUD and Renderer classes as members of GameEngine as highlighted in this next code.

class GameEngine extends SurfaceView implements Runnable,
GameStarter {
    private Thread mThread = null;
    private long mFPS;

    private GameState mGameState;
    private SoundEngine mSoundEngine;
    HUD mHUD;
    Renderer mRenderer;

Initialize the instances of the HUD and Renderer classes in the GameEngine constructor as highlighted next.

public GameEngine(Context context, Point size) {
   super(context);

   mGameState = new GameState(this, context);
   mSoundEngine = new SoundEngine(context);
   mHUD = new HUD(size);
   mRenderer = new Renderer(this);
}

Now we can add a call to the draw method of the Renderer class in the run method as highlighted next.

@Override
public void run() {
   while (mGameState.getThreadRunning()) {
          long frameStartTime = System.currentTimeMillis();

          if (!mGameState.getPaused()) {
            ...