Book Image

Learning Java by Building Android Games - Third Edition

By : John Horton
5 (1)
Book Image

Learning Java by Building Android Games - Third Edition

5 (1)
By: John Horton

Overview of this book

Android is one of the most popular mobile operating systems today. It uses the most popular programming language, Java, as one of the primary languages for building apps of all types. Unlike most other Android books, this book doesn’t assume that you have any prior knowledge of Java programming, instead helps you get started with building Android games as a beginner. This new, improved, and updated third edition of Learning Java by Building Android Games helps you to build Android games from scratch. Once you've got to grips with the fundamentals, the difficulty level increases steadily as you explore key Java topics, such as variables, loops, methods, object-oriented programming (OOP), and design patterns while working with up-to-date code and supporting examples. At each stage, you'll be able to test your understanding by implementing the concepts that you’ve learned to develop a game. Toward the end, you’ll build games such as Sub Hunter, Retro Pong, Bullet Hell, Classic Snake, and Scrolling Shooter. By the end of this Java book, you'll not only have a solid understanding of Java and Android basics but will also have developed five cool games for the Android platform.
Table of Contents (24 chapters)

Making sense of screen touches

We know that when the player touches the screen, the operating system calls our onTouchEvent method to give our code the opportunity to respond to the touch.

Furthermore, we have also seen that when the player touches the screen, the onTouchEvent method is called twice. We know this because of the debugging output we examined back in Chapter 2, Java – First Contact. You probably remember that the method is called for both the touch and release events.

To make our game respond correctly to touches, we will need to determine the actual event type and find out exactly where on the screen the touch occurred.

Look at the signature of the onTouchEvent method and pay special attention to the highlighted argument:

public boolean onTouchEvent(MotionEvent motionEvent) {

Even though our knowledge of classes and objects is still incomplete, our knowledge of methods should help us work out what is going on here. An object of the MotionEvent...