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Learning Java by Building Android  Games

You're reading from   Learning Java by Building Android Games Learn Java and Android from scratch by building six exciting games

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Product type Paperback
Published in Aug 2018
Publisher
ISBN-13 9781788839150
Length 774 pages
Edition 2nd Edition
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Author (1):
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John Horton John Horton
Author Profile Icon John Horton
John Horton
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Table of Contents (28) Chapters Close

Preface 1. Java, Android and Game Development 2. Java: First Contact FREE CHAPTER 3. Variables, Operators and Expressions 4. Structuring Code with Java Methods 5. The Android Canvas Class – Drawing to the Screen 6. Repeating Blocks of Code with Loops 7. Making Decisions with Java If, Else and Switch 8. Object-Oriented Programming 9. The Game Engine, Threads, and The Game Loop 10. Coding the Bat and Ball 11. Collisions, Sound Effects and Supporting Different Versions of Android 12. Handling Lots of Data with Arrays 13. Bitmap Graphics and Measuring Time 14. The Stack, the Heap, and the Garbage Collector 15. Android Localization -Hola! 16. Collections, Generics and Enumerations 17. Manipulating Bitmaps and Coding the Snake class 18. Introduction to Design Patterns and much more! 19. Listening with the Observer Pattern, Multitouch and Building a Particle System 20. More Patterns, a Scrolling Background and Building the Player's ship 21. Completing the Scrolling Shooter Game 22. Exploring More Patterns and Planning the Platformer Project 23. The Singleton Pattern, Java HashMap, Storing Bitmaps Efficiently and Designing Levels 24. Sprite-sheet animations, Controllable Player and Parallax Scrolling Backgrounds 25. Intelligent Platforms and Advanced Collision Detection 26. What next? Index

Making sense of the 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 two. 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 first determine the actual event type and secondly 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 sketchy, our knowledge of methods should help us work out what is going on here. An object of type MotionEvent named motionEvent is passed into the method...

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