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

Interfaces versus abstract classes

Now that we've covered both abstract classes and interfaces, you might be wondering what you should use when you are building your app. They look similar in some ways, but there are some important differences that we'll cover now, which will make it easier for you to choose which one to use.

We've already mentioned that Kotlin doesn't allow multiple inheritance. Take a look at this example:

abstract class InsureBase {
abstract fun insure()

abstract class CarBase {
abstract fun drive()

//compiler error, can't inherit from multiple classes
class InsurableCar: InsureBase(), CarBase() {
override fun insure() {

override fun drive() {

This won't compile, because we are trying to inherit from two classes.

Interfaces don't have that limitation; a class can implement as many interfaces as it wants. So, if we want to have a type that can be both driven and insured, we can have two interfaces that define that behavior and one concrete class that implements...