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)

States move in one direction only

Once a state has been reached, a job will not move back to a previous state. Consider the following application:

fun main(args: Array<String>) = runBlocking {
val time = measureTimeMillis {
val job = launch {
delay(2000)
}

// Wait for it to complete once
job.join()

// Restart the Job
job.start()
job.join()
}
println("Took $time ms")
}

This code creates a job that suspends execution for 2 seconds. Once the job completes on the first call to job.join(), the start() function is called on job with the intent of restarting it, followed by a second call to join() to wait for the second execution to complete. The complete time of execution was measured and stored in the time variable.

Let's see how long the execution of this code takes:

As you can see, the...