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)
Part 1: Fundamentals of Jetpack Compose
Part 2: Building User Interfaces
Part 3: Advanced Topics

Managing State of Your Composable Functions

In Chapter 4, Laying Out UI Elements in Compose, I showed you how to set the red, green, and blue portions of a color by dragging sliders. We used state to store the color portions and passed simple values and callbacks that are invoked when value changes are due to composable functions. Quite a few other sample apps of the previous chapters dealt with state too. In fact, reacting to state changes is critical to how modern mobile apps work.

So far, I have described state as data that can change over time. You learned about a few important functions – for example, remember { } and mutableStateOf(). I also briefly touched on a concept called state hoisting.

This chapter builds on these foundations. For example, you will understand the difference between stateless and stateful composables, and when to choose which. Also, I will show you how events should flow in a well-behaved Compose app.

The main sections of this chapter are...