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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 five exciting games

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Product type Paperback
Published in Mar 2021
Publisher Packt
ISBN-13 9781800565869
Length 686 pages
Edition 3rd 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 (24) Chapters Close

Preface 1. Chapter 1: Java, Android, and Game Development 2. Chapter 2: Java – First Contact FREE CHAPTER 3. Chapter 3: Variables, Operators, and Expressions 4. Chapter 4: Structuring Code with Java Methods 5. Chapter 5: The Android Canvas Class – Drawing to the Screen 6. Chapter 6: Repeating Blocks of Code with Loops 7. Chapter 7: Making Decisions with Java If, Else, and Switch 8. Chapter 8: Object-Oriented Programming 9. Chapter 9: The Game Engine, Threads, and the Game Loop 10. Chapter 10: Coding the Bat and Ball 11. Chapter 11: Collisions, Sound Effects, and Supporting Different Versions of Android 12. Chapter 12: Handling Lots of Data with Arrays 13. Chapter 13: Bitmap Graphics and Measuring Time 14. Chapter 14: Java Collections, the Stack, the Heap, and the Garbage Collector 15. Chapter 15: Android Localization – Hola! 16. Chapter 16: Collections and Enumerations 17. Chapter 17: Manipulating Bitmaps and Coding the Snake Class 18. Chapter 18: Introduction to Design Patterns and Much More! 19. Chapter 19: Listening with the Observer Pattern, Multitouch, and Building a Particle System 20. Chapter 20: More Patterns, a Scrolling Background, and Building the Player's Ship 21. Chapter 21: Completing the Scrolling Shooter Game 22. Chapter 22: What Next? 23. Other Books You May Enjoy

How to use variables

That's enough theory. Let's learn how to 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 the int type, with the name score, we would type the following:

int score;

That's it. Simply state the type – in this case, int – and then leave a space and type the name you want to use for the variable. Also, note the semicolon ;, at the end of the line. This will tell the compiler that we are done with this line and that 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...

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