Book Image

How to Build Android Apps with Kotlin

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

How to Build Android Apps with Kotlin

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

Overview of this book

Are you keen to get started building Android 11 apps, but don’t know where to start? How to Build Android Apps with Kotlin is a comprehensive guide that will help kick-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 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. Moving ahead, you'll get to grips with testing, learn how to keep your architecture clean, understand how to persist data, and gain 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 (17 chapters)
Preface
12
12. Dependency Injection with Dagger and Koin

Coroutines

Coroutines were added in Kotlin 1.3 for managing 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 function...