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Android Programming with Kotlin for Beginners

You're reading from   Android Programming with Kotlin for Beginners Build Android apps starting from zero programming experience with the new Kotlin programming language

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Product type Paperback
Published in Apr 2019
Publisher Packt
ISBN-13 9781789615401
Length 698 pages
Edition 1st Edition
Languages
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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 (31) Chapters Close

Preface 1. Getting Started with Android and Kotlin FREE CHAPTER 2. Kotlin, XML, and the UI Designer 3. Exploring Android Studio and the Project Structure 4. Getting Started with Layouts and Material Design 5. Beautiful Layouts with CardView and ScrollView 6. The Android Lifecycle 7. Kotlin Variables, Operators, and Expressions 8. Kotlin Decisions and Loops 9. Kotlin Functions 10. Object-Oriented Programming 11. Inheritance in Kotlin 12. Connecting Our Kotlin to the UI and Nullability 13. Bringing Android Widgets to Life 14. Android Dialog Windows 15. Handling Data and Generating Random Numbers 16. Adapters and Recyclers 17. Data Persistence and Sharing 18. Localization 19. Animations and Interpolations 20. Drawing Graphics 21. Threads and Starting the Live Drawing App 22. Particle Systems and Handling Screen Touches 23. Android Sound Effects and the Spinner Widget 24. Design Patterns, Multiple Layouts, and Fragments 25. Advanced UI with Paging and Swiping 26. Advanced UI with Navigation Drawer and Fragment 27. Android Databases 28. A Quick Chat Before You Go A. Other Book You May Enjoy Index

Handling large amounts of data with arrays

You might be wondering what happens when we have an app with lots of variables to keep track of. What about our Note to self app with 100 notes, or a high-score table in a game with the top 100 scores? We can declare and initialize 100 separate variables as follows:

var note1 = Note()
var note2 = Note()
var note3 = Note()
// 96 more lines like the above
var note100 = Note()

Or, by using the high scores example we might use something like the following code:

var topScore1: Int
var topScore2: Int
// 96 more lines like the above
var topScore100: Int

Immediately, this code can seem unwieldy, but what about when someone gets a new top score, or if we want to let our users sort the order that their notes are displayed in? Using the high scores scenario, we must shift the scores in every variable down one place. This is the beginning of a nightmare, as shown in the following code:

topScore100 = topScore99;
topScore99 = topScore98;
topScore98 = topScore97;...
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