Book Image

Kotlin Quick Start Guide

By : Marko Devcic
Book Image

Kotlin Quick Start Guide

By: Marko Devcic

Overview of this book

Kotlin is a general purpose, object-oriented language that primarily targets the JVM and Android. Intended as a better alternative to Java, its main goals are high interoperability with Java and increased developer productivity. Kotlin is still a new language and this book will help you to learn the core Kotlin features and get you ready for developing applications with Kotlin. This book covers Kotlin features in detail and explains them with practical code examples.You will learn how to set up the environment and take your frst steps with Kotlin and its syntax. We will cover the basics of the language, including functions, variables, and basic data types. With the basics covered, the next chapters show how functions are first-class citizens in Kotlin and deal with the object-oriented side of Kotlin. You will move on to more advanced features of Kotlin. You will explore Kotlin's Standard Library and learn how to work with the Collections API. The book finishes by putting Kotlin in to practice, showing how to build a desktop app. By the end of this book, you will be confident enough to use Kotlin for your next project.
Table of Contents (15 chapters)
Title Page
Copyright and Credits
Packt Upsell


We've already seen how Kotlin can use the object keyword to create an anonymous instance of a class. This can be used when we want to pass some functionality as an argument to another method. But if the interface or a class you are creating has only one function, then using anonymous classes may feel cumbersome and too verbose.

This is where lambda expressions, or lambdas for short, come into play. Lambdas can be best described as short pieces of code that can be passed to other functions. If you have a Java background, then you probably remember how Java 8 was highly anticipated because it finally brought support for lambdas.

In UI programming, event listeners are the perfect use case for lambdas. We're going to take a look at an example from Android. Android still uses Java 6, and there we can't use Java lambdas, so it will be perfect to show how using Kotlin instead of Java is less verbose if you can't use the latest Java versions. On android with Java, you would set a click listener...