Book Image

How to Build Android Apps with Kotlin - Second Edition

By : Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal
Book Image

How to Build Android Apps with Kotlin - Second Edition

By: Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal

Overview of this book

Looking to kick-start your app development journey with Android 13, but don’t know where to start? How to Build Android Apps with Kotlin is a comprehensive guide that will help jump-start your Android development practice. This book starts with the fundamentals of app development, enabling you to utilize Android Studio and Kotlin to get started with building Android projects. You'll learn how to create apps and run them on virtual devices through guided exercises. Progressing through the chapters, you'll delve into Android's RecyclerView to make the most of lists, images, and maps, and see how to fetch data from a web service. You'll also get to grips with testing, learning how to keep your architecture clean, understanding how to persist data, and gaining basic knowledge of the dependency injection pattern. Finally, you'll see how to publish your apps on the Google Play store. You'll work on realistic projects that are split up into bitesize exercises and activities, allowing you to challenge yourself in an enjoyable and attainable way. You'll build apps to create quizzes, read news articles, check weather reports, store recipes, retrieve movie information, and remind you where you parked your car. By the end of this book, you'll have the skills and confidence to build your own creative Android applications using Kotlin.
Table of Contents (24 chapters)
1
Part 1: Android Foundation
6
Part 2: Displaying Network Calls
12
Part 3: Testing and Code Structure
17
Part 4: Polishing and Publishing an App

Using Coroutines on Android

Coroutines were added in Kotlin 1.3 to manage background tasks such as making network calls and accessing files or databases. Kotlin coroutines are Google’s official recommendation for asynchronous programming on Android. Their Jetpack libraries, such as LifeCycle, WorkManager, and Room, now include support for coroutines.

With coroutines, you can write your code in a sequential way. The long-running task can be made into a suspending function, which, when called, can pause the thread without blocking it. When the suspending function is done, the current thread will resume execution. This will make your code easier to read and debug.

To mark a function as a suspending function, you can add the suspend keyword to it; for example, if you have a function that calls the getMovies function, which fetches movies from your endpoint and then displays it:

val movies = getMovies()
displayMovies(movies)

You can make the getMovies() function a suspending...