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Android UI Development with Jetpack Compose

You're reading from   Android UI Development with Jetpack Compose Bring declarative and native UIs to life quickly and easily on Android using Jetpack Compose

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Product type Paperback
Published in Feb 2022
Publisher Packt
ISBN-13 9781801812160
Length 248 pages
Edition 1st Edition
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Author (1):
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Thomas Künneth Thomas Künneth
Author Profile Icon Thomas Künneth
Thomas Künneth
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Table of Contents (16) Chapters Close

Preface 1. Part 1:Fundamentals of Jetpack Compose
2. Chapter 1: Building Your First Compose App FREE CHAPTER 3. Chapter 2: Understanding the Declarative Paradigm 4. Chapter 3: Exploring the Key Principles of Compose 5. Part 2:Building User Interfaces
6. Chapter 4: Laying Out UI Elements 7. Chapter 5: Managing the State of Your Composable Functions 8. Chapter 6: Putting Pieces Together 9. Chapter 7: Tips, Tricks, and Best Practices 10. Part 3:Advanced Topics
11. Chapter 8: Working with Animations 12. Chapter 9: Exploring Interoperability APIs 13. Chapter 10: Testing and Debugging Compose Apps 14. Chapter 11: Conclusion and Next Steps 15. Other Books You May Enjoy

Looking closer at composable functions

The UI of a Compose app is built by writing and calling composable functions. We have already done both in the previous chapters, but my explanations regarding the structure of a composable, as well as its internals, have been quite basic – it's time to fix that.

Building blocks of composable functions

A composable function is a Kotlin function that has been annotated with @Composable.
All composables must be marked this way because the annotation informs the Compose compiler that the function converts data into UI elements.

The signature of a Kotlin function consists of the following parts or building blocks:

  • An optional visibility modifier (private, protected, internal, or public)
  • The fun keyword
  • A name
  • A list of parameters (can be empty) or, optionally, a default value
  • An optional return type
  • A block of code

Let's explore these parts in greater detail.

The default visibility...

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