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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 FREE CHAPTER 2. Java: First Contact 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

Polymorphism


We already know that polymorphism means different forms. But what does it mean to us?

Boiled down to its simplest:

Note

Any subclass can be used as part of the code that uses the superclass.

This means we can write code that is simpler and easier to understand, and easier to modify or change.

Also, we can write code for the superclass and rely on the fact that no matter how many times it is sub-classed, within certain parameters, the code will still work. Let's discuss an example.

Supposing we want to use polymorphism to help write a zoo management game. We will probably want to have a method like feed. We will probably want to pass a reference to the animal to be fed, into the feed method. This might seem like we need to write a feed method for each type of Animal.

However, we can write polymorphic methods with polymorphic return types and arguments.

Animal feed(Animal animalToFeed){
   // Feed any animal here
   return animalToFeed;
}

The method above has an Animal as a parameter...

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