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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

Reloading data with SharedPreferences

Let's see how we can reload our data the next time the app is run. This code will reload the three values that the previous code saved. We could even declare our variables and initialize them with the stored values:

String username  = 
   prefs.getString("username", "new user");
int age  = prefs.getInt("age", -1);
boolean subscribed = 
   prefs.getBoolean("newsletter-subscriber", false)

In the previous code, we load the data from disk using the method appropriate for the data type and the same label we used to save the data in the first place. What is less clear is the second argument to each of the method calls.

The getString, getInt, and getBoolean methods require a default value as the second parameter. If there is no data stored with that label, it will then return the default value.

We could then check for these default values in our...

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