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Simplifying Android Development with Coroutines and Flows

Simplifying Android Development with Coroutines and Flows

By : Jomar Tigcal
5 (2)
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Simplifying Android Development with Coroutines and Flows

Simplifying Android Development with Coroutines and Flows

5 (2)
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.
Table of Contents (11 chapters)
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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
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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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Unit testing suspending functions

In this section, we will focus on how you can unit test your suspending functions. You can create unit tests for classes such as ViewModel that launch a coroutine or have suspending functions.

Creating a unit test for a suspending function is more difficult to write as a suspending function can only be called from a coroutine or another coroutine. What you can do is use the runBlocking coroutine builder and call the suspending function from there. For example, say you have a MovieRepository class like the following:

class MovieRepository (private val movieService:
  MovieService) {
    ...
    private val movieLiveData =
      MutableLiveData<List<Movie>>()
    fun fetchMovies() {
        ...
        val movies = movieService.getMovies...
End of Section 4
Next Section
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