Kotlin Coroutines and Flow for Android Development 2023

The Complete Guide! Get a deep understanding of Kotlin Coroutines and Flow to use them successfully in your Android Apps

What you'll learn
Implement the most common use cases for Kotlin Coroutines and Flow on Android
Get a deep understanding of Kotlin Coroutines and Flows
Learn advanced Coroutine Concepts (Structured Concurrency, Coroutine Scopes and Contexts, internal workings, )
Learn how to create Flows using different Flow builders
Learn about Flow operators (lifecycle operators, intermediate operators, terminal operators)
Learn about different kind of Flows (regular Flows, SharedFlows, StateFlows)
Create a stock live-tracking app with Flows
Learn when to use Channels in Android Development
Understand the advantages of using Coroutines over Callbacks or RxJava.
How to perform network requests with Retrofit sequentially and concurrently.
How to use Room together with Coroutines.
Background processing with Coroutines.
Exception Handling and Cancellation in Coroutines and Flows.
How to write Unit Tests for coroutine-based implementations

Requirements
No prior knowledge about Kotlin Coroutines or Flow needed, however you should be familiar with the Basics of Kotlin and Android, as well as some Android Jetpack Components (ViewModels, LiveData, Room) and Retrofit.
Description
Google recommends Kotlin Coroutines and Flow as the preferred solution for asynchronous programming on Android. Sooner or later, probably every Android developer will get in touch with these topics.



This course will give you a deep understanding of Kotlin Coroutines and Flow and show how to implement the most common use cases for Android applications.



This course consists of two big parts: The Coroutines part and the Flow part.

Before being able to use Flows in our applications, we first need a solid understanding of Coroutines. That’s why Coroutines are covered first. However, if you already have some experience with Coroutines, then you can also start with the Flow part right away, and jump back to lessons of the Coroutines part whenever needed.



In the part about Coroutines, first, we will take a detailed look at the advantages of Kotlin Coroutines over other approaches for asynchronous programming, like RxJava and Callbacks.



Then, we will talk about some theoretical fundamentals. These include:

Routines vs. Coroutines

Suspend Functions

Coroutines vs. Threads

Blocking vs. Suspending

Multithreaded Coroutines

Internal workings



Next, we will implement some of the most common use cases for Kotlin Coroutines in Android applications. These include:

Performing network requests with Retrofit sequentially and concurrently

Implementing Timeouts and Retries

Using Room with Coroutines

Performing background processing with Coroutines

Continuing Coroutine execution even when the user leaves the screen.



To improve your learning experience, this course also challenges you with several exercises.



Learning Coroutines can be overwhelming because you need to learn a lot of new concepts. However, we are going to start simple and as our use cases will get more and more complex, we will learn about new concepts step-by-step. These new concepts are:

Coroutine Builders (launch, async, runBlocking)

Coroutine Context

Coroutine Dispatchers

Structured Concurrency

Coroutine Scopes (viewModelScope, lifecycleScope, GlobalScope)

Jobs and SupervisorJobs

scoping functions (coroutineScope{} and supervisorScope{})

Cooperative Cancellation

Non-Cancellable Code



We will also make a deep dive into Exception Handling and discuss concepts like:

exception handling with try/catch

exception handling with CoroutineExceptionHandlers

when to use try/catch and when to use a CoroutineExceptionHandler

exception handling in Coroutines started with launch and async

exception handling specifics of scoping functions coroutineScope{} and supervisorScope{}



Unit Tests are very important for every codebase. In the course's final section, we will write unit tests for most of the coroutine-based use cases we implemented earlier. We will discuss concepts like

TestCoroutineDispatcher

creating a JUnit4 Rule for testing coroutine-based code

runBlockingTest{} Coroutine Builder

virtual time

Testing sequential and concurrent execution

TestCoroutineScope



In the part about Kotlin Flow, we first cover all the basics. We will answer the question “What is a Flow?” and then we discuss the benefits and drawbacks of reactive programming.



Afterward, we are going to have a look at different Flow builders and operators:

basic flow builders

terminal operators

terminal operator “launchIn()”

terminal operator “asLiveData()”

lifecycle operators

intermediate operators



In our first real Flow use case, we use a Flow to create a live stock-tracking feature, that uses all the available basic flow components.



In the next module, we will take a look at Exception Handling and Cancellation with Kotlin Flow.



In the following module, you will learn about StateFlow and SharedFlow and the following concepts:

how to make Coroutines lifecycle-aware with the “repeatOnLifecycle()” suspend function

Hot Flows VS Cold Flows

Converting Flows to SharedFlows with the “shareIn()” operator

Converting Flows to StateFlows with the “stateIn()” operator

When to use SharedFlow and when to use StateFlow



Next, you will learn about Channels, how they differ from hot flows, and when they are useful in Android Applications.



By the end of this course, you will have a fundamental understanding of Kotlin Coroutines and Flows and be able to write readable and maintainable, asynchronous, and multithreaded Android Applications.

Who this course is for:
Android Developers who want to get a deep understanding of Kotlin Coroutines and Flow and want to know how to implement the most common use cases on Android.