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.
Table of Contents (11 chapters)
1
Part 1 – Kotlin Coroutines on Android
6
Part 2 – Kotlin Flows on Android

Handling Flow completion

In this section, we will explore how to handle Flow completion. We can add code to perform additional tasks after our Flows have completed.

When the Flow encounters an exception, it will be canceled and complete the Flow. A Flow is also completed when the last element of the Flow has been emitted.

To add a listener in your Flow when it has completed, you can use the onCompletion operator and add the code block that will be run when the Flow completes. A common usage of onCompletion is hiding the ProgressBar in your UI when the Flow has completed, as shown in the following code:

class MainActivity : AppCompatActivity() {
  ...
  override fun onCreate(savedInstanceState: Bundle?) {
      ...
      lifecycleScope.launch {
          repeatOnLifecycle(Lifecycle.State.STARTED) {
     ...