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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
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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

Variables


We can think of a variable as a named storage box. We choose a name, perhaps variableA. These names are the programmer's access into the memory of the user's Android device.

Variables are values in memory that are ready to be used when necessary by referring to them with their name.

Computer memory has a highly complex system of addresses that, fortunately, we do not need to directly interact with. Kotlin variables allow us to devise our own convenient names for all the data that we need our app to work with. The operating system will, in turn, interact with the physical (hardware) memory.

So, we can think of our Android device's memory as a huge warehouse waiting for us to add our variables. When we assign names to our variables, they are stored in the warehouse, ready for when we need them. When we use our variable's name, the device knows exactly what we are referring to. We can then tell it to do things, such as the following:

  • Assign a value to variableA

  • Add variableA to variableB...

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