Book Image

Android UI Development with Jetpack Compose

By : Thomas Künneth
Book Image

Android UI Development with Jetpack Compose

By: Thomas Künneth

Overview of this book

Jetpack Compose is Android’s new framework for building fast, beautiful, and reliable native user interfaces. It simplifies and significantly accelerates UI development on Android using the declarative approach. This book will help developers to get hands-on with Jetpack Compose and adopt a modern way of building Android applications. The book is not an introduction to Android development, but it will build on your knowledge of how Android apps are developed. Complete with hands-on examples, this easy-to-follow guide will get you up to speed with the fundamentals of Jetpack Compose such as state hoisting, unidirectional data flow, and composition over inheritance and help you build your own Android apps using Compose. You'll also cover concepts such as testing, animation, and interoperability with the existing Android UI toolkit. By the end of the book, you'll be able to write your own Android apps using Jetpack Compose.
Table of Contents (16 chapters)
Part 1:Fundamentals of Jetpack Compose
Part 2:Building User Interfaces
Part 3:Advanced Topics

Hoisting state and passing events

So, state is any value that can change over time. As Jetpack Compose is a declarative UI framework, the only way to update a composable is to call it with new arguments. This happens automatically when state a composable is using changes. State hoisting is a pattern of moving state up to make a composable stateless.

Besides making a composable more easily reusable and testable, moving state up is necessary to use it in more than one composable function. You have already seen this in quite a few of my sample apps. For example, in the Composing and recomposing the UI section of Chapter 3, Exploring the Key Principles of Compose, we used three sliders to create and display a color.

While state controls the visual representation of a composable function (that is, how it looks on screen), events notify a part of a program that something has happened. Let's focus a little more on this. My sample FlowOfEventsDemo app is a simple temperature converter...