Book Image

Learning Concurrency in Kotlin

By : Miguel Angel Castiblanco Torres
Book Image

Learning Concurrency in Kotlin

By: Miguel Angel Castiblanco Torres

Overview of this book

Kotlin is a modern and statically typed programming language with support for concurrency. Complete with detailed explanations of essential concepts, practical examples and self-assessment questions, Learning Concurrency in Kotlin addresses the unique challenges in design and implementation of concurrent code. This practical guide will help you to build distributed and scalable applications using Kotlin. Beginning with an introduction to Kotlin's coroutines, you’ll learn how to write concurrent code and understand the fundamental concepts needed to write multithreaded software in Kotlin. You'll explore how to communicate between and synchronize your threads and coroutines to write collaborative asynchronous applications. You'll also learn how to handle errors and exceptions, as well as how to work with a multicore processor to run several programs in parallel. In addition to this, you’ll delve into how coroutines work with each other. Finally, you’ll be able to build an Android application such as an RSS reader by putting your knowledge into practice. By the end of this book, you’ll have learned techniques and skills to write optimized code and multithread applications.
Table of Contents (11 chapters)

Creating a coroutine to call a service

Now it's a good time to add a call to a service. To start with something simple, we will use Java's DocumentBuilder to call an RSS feed for us. First, we will add a variable to hold the DocumentBuilderFactory below where we put the dispatcher:

private val dispatcher = newSingleThreadContext(name = "ServiceCall")
private val factory = DocumentBuilderFactory.newInstance()

The second step is to create a function that will do the actual call:

private fun fetchRssHeadlines(): List<String> {
val builder = factory.newDocumentBuilder()
val xml = builder.parse("")
return emptyList()

Notice how the function is, for now, returning an empty list of strings after calling the feed. The idea is to implement this function so that it returns the headlines of the given feed. But...