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

How to use variables


That's enough theory. Let's see how we would use our variables and types. Remember that each primitive type needs a specific amount of real device memory. This is one of the reasons that the compiler needs to know what type a variable will be. So, we must first declare a variable and its type before we try to do anything with it.

Declaring variables

To declare a variable of type int with the name score, we would type:

int score;

That's it. Simply state the type, in this case, int, then leave a space and type the name you want to use for the variable. Note also the semicolon ; on the end of the line will tell the compiler that we are done with this line and what follows, if anything, is not part of the declaration.

Similarly, for almost all the other variable types, the declaration would occur in the same way. Here are some examples. This process is like reserving a labeled storage box in the warehouse. The variable names used next are arbitrary.

long millisecondsElapsed;
float...