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

Spawning an array of bullets


Now we know the basics of arrays we can get started spawning a load of bullets at the same time and store them in an array.

Note

Make sure you deleted the temporary code from the Spawning a bullet section before proceeding.

Add a few control variables and declare an array of bullets as a member of BulletHellGame. Add this code just before the constructor.

// Up to 10000 bullets
private Bullet[] mBullets = new Bullet[10000];
private int mNumBullets = 0;
private int mSpawnRate = 1;

private Random mRandomX = new Random();
private Random mRandomY = new Random();

We have an array called mBullets, capable of holding 10000 bullets. The new keyword initializes the array, not the Bullets within the array. We also have two int variables to keep track of how many bullets we want to spawn each time the spawn method is called and how many bullets there are in total.

We also declare and initialize two objects of type Random which we will use to randomly generate screen positions...