Jetpack Compose is the future of Android UI. Master how it works internally and become a more efficient developer with it. You’ll also find it valuable if you are not an Android dev. This book provides all the details to understand how the Compose compiler & runtime work, and how to create a client library using them.

This book explores the guts of Jetpack Compose, the brand new library by Google and the Android team that will become the future of Android UI. Dedicating time now to learn about its internals in-depth will yield powerful skills to write modern and efficient Android apps in the future.

If you are interested in other use cases of Jetpack Compose rather than Android, this book has got you covered also. Jetpack Compose internals is very focused on exploring the compiler and runtime from a generic perspective, making the overall experience very agnostic of the target platform. The book also provides a chapter dedicated to diverse use cases for Jetpack Compose, which exposes a few really interesting examples over code.

Jetpack Compose and Android are trademarks of Google LLC and this book is not endorsed by or affiliated with Google in any way.

Why to read this book

Jetpack Compose will become the “de facto” standard for UI in the Android platform sooner than later, and even if lots of apps will still use the View system, new screens will be coded using Compose instead, so it will become an unavoidable thing to learn. My strong suggestion is to dedicate some time to learn about its internals in-depth, since that will yield powerful skills to write modern and efficient Android apps.

In the other hand, if you are interested in other use cases of Jetpack Compose rather than Android, you’ll likely be very happy to know that this book has got you covered also. Jetpack Compose internals is very focused on the compiler and runtime details, making the overall experience very agnostic of the target platform. Having an Android background should not be a requirement for reading the book. The book also provides a chapter dedicated to diverse use cases for Jetpack Compose, which exposes a few really interesting examples over code.

What this book is not about

This book does not try to replicate the Jetpack Compose official documentation, which is quite good already and the source of truth for any newcomers to the library. For that reason you will not find listings or catalogues with all the existing components or apis that the library provides in the book.

If learning Compose is what you are looking for, I’d recommend you to go ahead and subscribe to the “Practical Jetpack Compose” by Joe Birch. Joe’s book is full of interesting examples and detailed explanations about all the relevant use cases of Jetpack Compose. That is a highly valuable reference book to have on your desk if you are an Android developer. The book is still under work, but will be released later this year.

What this book is about

This books heavily focuses on the internals of Jetpack Compose. As an Android developer and over the years, I have grown a feeling of how astoundingly important can become to learn about internals of the platform you work with every day. That helps me a lot to understand what code I want to write. Having that type of knowledge allows me to write performant code that complies to the platform expectations instead of going against them, and allows me to understand why things work the way they do. To me, this is probably one of the biggest differences between non very experienced and experienced Android developers.

For many years we have all been diving into lower aspects of the platform like layout and draw passes, drawing efficiency, internals of the View system, styles and themes, lifecycles, and much more. This book is an opportunity to do the same but for Jetpack Compose, and open your mind in terms of how to think about it, given how important it is going to become for the years to come. My personal goal as the author of this book is to give you all the tools to achieve a big leap on this field.

Table of Contents

1. Composable functions

2. The Compose compiler

3. The Compose runtime

4. Compose UI

5. State snapshot system

6. Effects and effect handlers

7. Advanced Compose Runtime use cases

About the Author

Jorge Castillo is a Google Developer Expert (GDE) for Android and Kotlin that has been traditionally very active in the Android community.