Book Image

Simplifying Android Development with Coroutines and Flows

By : Jomar Tigcal
Book Image

Simplifying Android Development with Coroutines and Flows

By: Jomar Tigcal

Overview of this book

Coroutines and flows are the new recommended way for developers to carry out asynchronous programming in Android using simple, modern, and testable code. This book will teach you how coroutines and flows work and how to use them in building Android applications, along with helping you to develop modern Android applications with asynchronous programming using real data. The book begins by showing you how to create and handle Kotlin coroutines on Android. You’ll explore asynchronous programming in Kotlin, and understand how to test Kotlin coroutines. Next, you'll learn about Kotlin flows on Android, and have a closer look at using Kotlin flows by getting to grips with handling flow cancellations and exceptions and testing the flows. By the end of this book, you'll have the skills you need to build high-quality and maintainable Android applications using coroutines and flows.

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Table of Contents (11 chapters)
Preface
Preface
Who this book is for
What this book covers
To get the most out of this book
Download the example code files
Conventions used
Get in touch
Share Your Thoughts
1
Part 1 – Kotlin Coroutines on Android
Part 1 – Kotlin Coroutines on Android
Free Chapter
2
Chapter 1: Introduction to Asynchronous Programming in Android
Chapter 1: Introduction to Asynchronous Programming in Android
Technical requirements
Understanding asynchronous programming
Exploring threads, AsyncTasks, and Executors
The new way to do it – coroutines and flows
Summary
Further reading
3
Chapter 2: Understanding Kotlin Coroutines
Chapter 2: Understanding Kotlin Coroutines
Technical requirements
Creating coroutines in Android
Exploring coroutine builders, scopes, and dispatchers
Understanding coroutine contexts and jobs
Exercise – using coroutines in an Android app
Summary
4
Chapter 3: Handling Coroutine Cancelations and Exceptions
Chapter 3: Handling Coroutine Cancelations and Exceptions
Technical requirements
Canceling coroutines
Managing coroutine timeouts
Catching exceptions in coroutines
Summary
5
Chapter 4: Testing Kotlin Coroutines
Chapter 4: Testing Kotlin Coroutines
Technical requirements
Setting up an Android project for testing coroutines
Unit testing suspending functions
Testing coroutines
Exercise 4.01 – adding tests to coroutines in an Android app
Summary
Further reading
6
Part 2 – Kotlin Flows on Android
Part 2 – Kotlin Flows on Android
7
Chapter 5: Using Kotlin Flows
Chapter 5: Using Kotlin Flows
Technical requirements
Using Flows in Android
Creating Flows with Flow builders
Using operators with Flows
Buffering and combining flows
Exploring StateFlow and SharedFlow
Exercise 5.01 – Using Kotlin Flow in an Android app
Summary
8
Chapter 6: Handling Flow Cancelations and Exceptions
Chapter 6: Handling Flow Cancelations and Exceptions
Technical requirements
Canceling Kotlin Flows
Retrying tasks with Flow
Catching exceptions in Flows
Handling Flow completion
Exercise 6.01 – Handling Flow exception in an Android app
Summary
9
Chapter 7: Testing Kotlin Flows
Chapter 7: Testing Kotlin Flows
Technical requirements
Setting up an Android project for testing Flows
Testing Kotlin Flows
Testing Flows with Turbine
Exercise 7.01 – Adding tests to Flows in an Android app
Summary
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10
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Exercise 7.01 – Adding tests to Flows in an Android app

For this exercise, you will be continuing the movie app you worked on in Exercise 6.01 – Handling Flow exception in an Android app. This application displays the movies that are currently playing in movie theatres. You will be adding tests for the Kotlin Flows in the project by following these steps:

  1. Open in Android Studio the movie app you worked on in Exercise 6.01 – Handling Flow exception in an Android app.
  2. Go to the MovieViewModelTest class. Run the test class, and the fetchMovies() test function will fail. That is because we changed the implementation to use Flow in the previous chapter.
  3. Remove the content of the fetchMovies() test function and replace it with the following content:
    @Test
fun fetchMovies() {
    val dispatcher = StandardTestDispatcher()
 
    val movies = listOf(Movie(title = "Movie"))
    val expectedMovies...
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