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Android Programming for Beginners

You're reading from   Android Programming for Beginners Build in-depth, full-featured Android apps starting from zero programming experience

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Product type Paperback
Published in Apr 2021
Publisher Packt
ISBN-13 9781800563438
Length 742 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 (30) Chapters Close

Preface 1. Chapter 1: Beginning Android and Java 2. Chapter 2: First Contact: Java, XML, and the UI Designer FREE CHAPTER 3. Chapter 3: Exploring Android Studio and the Project Structure 4. Chapter 4: Getting Started with Layouts and Material Design 5. Chapter 5: Beautiful Layouts with CardView and ScrollView 6. Chapter 6: The Android Lifecycle 7. Chapter 7: Java Variables, Operators, and Expressions 8. Chapter 8: Java Decisions and Loops 9. Chapter 9: Learning Java Methods 10. Chapter 10: Object-Oriented Programming 11. Chapter 11: More Object-Oriented Programming 12. Chapter 12: The Stack, the Heap, and the Garbage Collector 13. Chapter 13: Anonymous Classes – Bringing Android Widgets to Life 14. Chapter 14: Android Dialog Windows 15. Chapter 15: Arrays, Maps, and Random Numbers 16. Chapter 16: Adapters and Recyclers 17. Chapter 17: Data Persistence and Sharing 18. Chapter 18: Localization 19. Chapter 19: Animations and Interpolations 20. Chapter 20: Drawing Graphics 21. Chapter 21: Threads and Starting the Live Drawing App 22. Chapter 22: Particle Systems and Handling Screen Touches 23. Chapter 23: Supporting Different Versions of Android, Sound Effects, and Spinner Widget 24. Chapter 24: Design Patterns, Multiple Layouts, and Fragments 25. Chapter 25: Building a Simple Image Gallery App 26. Chapter 26: Advanced UI with Navigation Drawer and Fragment 27. Chapter 27: Android Databases 28. Chapter 28: A Quick Chat before You Go 29. Other Books You May Enjoy

Getting dynamic with arrays

As we discussed at the beginning of all this array stuff, if we need to declare and initialize each element of an array individually, there isn't a huge amount of benefit to an array over regular variables. Let's look at an example of declaring and initializing arrays dynamically.

Dynamic array example

Let's make a simple dynamic array example. You can get the working project for this example in the download bundle. It is at Chapter 15/Dynamic Array Example/MainActivity.java.

Create a project using the Empty Activity template and call it Dynamic Array Example.

Type the following code just after the call to the setContentView method in the onCreate method. See whether you can work out what the output will be before we discuss it and analyze the code:

// Declaring and allocating in one step
int[] ourArray = new int[1000];
// Let's initialize ourArray using a for loop
// Because more than a few variables is allot of typing...
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