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)

Iterators

Iterators are particularly useful to go through a collection of elements in order. Some characteristics of Kotlin's iterators are:

  • They can't retrieve an element by index, so elements can only be accessed in order
  • They have the function hasNext(), which indicates whether there are more elements
  • Elements can be retrieved in a single direction only; there's no way to retrieve previous elements
  • They can't be reset, so they can only be iterated once

To create a suspending iterator, we use the builder buildIterator(), passing it a lambda with the body of the iterator. This will return an Iterator<T> where T will be determined by the elements that the iterator yields, unless otherwise specified:

val iterator = buildIterator {
yield(1)
}

In this case, for example, iterator will be of type Iterator<Int>. If for some reason we want to override...