Book Image

Android UI Development with Jetpack Compose - Second Edition

By : Thomas Künneth
5 (1)
Book Image

Android UI Development with Jetpack Compose - Second Edition

5 (1)
By: Thomas Künneth

Overview of this book

Compose has caused a paradigm shift in Android development, introducing a variety of new concepts that are essential to an Android developer’s learning journey. It solves a lot of pain points associated with Android development and is touted to become the default way to building Android apps over the next few years. This second edition has been thoroughly updated to reflect all changes and additions that were made by Google since the initial stable release, and all examples are based on Material 3 (also called Material You). This book uses practical examples to help you understand the fundamental concepts of Jetpack Compose and how to use them when you are building your own Android applications. You’ll begin by getting an in-depth explanation of the declarative approach, along with its differences from and advantages over traditional user interface (UI) frameworks. Having laid this foundation, the next set of chapters take a practical approach to show you how to write your first composable function. The chapters will also help you master layouts, an important core component of every UI framework, and then move to more advanced topics such as animation, testing, and architectural best practices. By the end of this book, you’ll be able to write your own Android apps using Jetpack Compose and Material Design.
Table of Contents (18 chapters)
1
Part 1: Fundamentals of Jetpack Compose
5
Part 2: Building User Interfaces
10
Part 3: Advanced Topics

Composing and recomposing the UI

Unlike imperative UI frameworks, Jetpack Compose does not depend on the developer proactively modifying a component tree when changes in the app data require changes to be made to the UI. Instead, Jetpack Compose detects such changes on its own and updates only the affected parts.

As you know by now, a Compose UI is declared based on the current app data. In my previous examples, you have seen quite a few conditional expressions (such as if or when) that determine which composable function is called or which parameters it receives. So, we are describing the complete UI in our code. The branch that will be executed depends on the app data (state) during runtime. The web framework React has a similar concept called Virtual DOM. But doesn’t this contradict my saying Compose detects such changes on its own and updates only the affected parts?

Conceptually, Jetpack Compose regenerates the entire UI when changes need to be applied. This, of course...