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

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...