Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By : Alexey Soshin
Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By: Alexey Soshin

Overview of this book

This book shows you how easy it can be to implement traditional design patterns in the modern multi-paradigm Kotlin programming language, and takes you through the new patterns and paradigms that have emerged. This second edition is updated to cover the changes introduced from Kotlin 1.2 up to 1.5 and focuses more on the idiomatic usage of coroutines, which have become a stable language feature. You'll begin by learning about the practical aspects of smarter coding in Kotlin, as well as understanding basic Kotlin syntax and the impact of design patterns on your code. The book also provides an in-depth explanation of the classical design patterns, such as Creational, Structural, and Behavioral families, before moving on to functional programming. You'll go through reactive and concurrent patterns, and finally, get to grips with coroutines and structured concurrency to write performant, extensible, and maintainable code. By the end of this Kotlin book, you'll have explored the latest trends in architecture and design patterns for microservices. You’ll also understand the tradeoffs when choosing between different architectures and make informed decisions.
Table of Contents (17 chapters)
1
Section 1: Classical Patterns
6
Section 2: Reactive and Concurrent Patterns
11
Section 3: Practical Application of Design Patterns

Introducing coroutines

In addition to the threading model provided by Java, Kotlin also has a coroutines model. Coroutines might be considered lightweight threads, and we'll see what advantages they provide over an existing model of threads shortly.

The first thing you need to know is that coroutines are not part of the language. They are simply another library provided by JetBrains. For that reason, if we want to use them, we need to specify this in our Gradle configuration file; that is, build.gradle.kts:

dependencies { 
    ... 
    implementation("org.jetbrains.kotlinx:kotlinx-      coroutines-core:1.5.1") 
}

Important Note:

By the time you read this book, the latest version of the Coroutines library will be 1.6 or greater.

First, we will compare starting a new thread and a new coroutine.

Starting coroutines

We've already seen how to start a new thread in Kotlin in the...