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Hands-On Android UI Development

You're reading from   Hands-On Android UI Development Design and develop attractive user interfaces for Android applications

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Product type Paperback
Published in Nov 2017
Publisher Packt
ISBN-13 9781788475051
Length 348 pages
Edition 1st Edition
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Author (1):
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Jason Morris Jason Morris
Author Profile Icon Jason Morris
Jason Morris
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Table of Contents (15) Chapters Close

Preface 1. Creating Android Layouts 2. Designing Form Screens FREE CHAPTER 3. Taking Actions 4. Composing User Interfaces 5. Binding Data to Widgets 6. Storing and Retrieving Data 7. Creating Overview Screens 8. Designing Material Layouts 9. Navigating Effectively 10. Making Overviews Even Better 11. Polishing Your Design 12. Customizing Widgets and Layouts 13. Activity Lifecycle
14. Test Your Knowledge Answers

Updating by Delta Events


Up until this point, when the data changes in the database, the ClaimItemAdapter simply tells the RecyclerView that the data has changed. This is not the most efficient use of resources, because the RecyclerView doesn't actually know what in the model has changed, and it's forced to relayout the entire scene as though the entire model has changed (although it will reuse the widgets it has already pooled).

RecyclerView actually has a secondary mechanism that allows you to tell it what has changed, rather than just saying that the data has changed. This is provided through a series of notifications the signal single items, or ranges being added, removed, and moved. The problem is that in order to use these methods, you need to know what has actually changed.

Most developer's first instincts here will be to use more events and signal from the DAO or a delegate layer what is changing, and then catch those events in the Adapter and forward them to the RecyclerView. This...

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