Book Image

Kotlin Programming Cookbook

By : Aanand Shekhar Roy, Rashi Karanpuria
Book Image

Kotlin Programming Cookbook

By: Aanand Shekhar Roy, Rashi Karanpuria

Overview of this book

The Android team has announced first-class support for Kotlin 1.1. This acts as an added boost to the language and more and more developers are now looking at Kotlin for their application development. This recipe-based book will be your guide to learning the Kotlin programming language. The recipes in this book build from simple language concepts to more complex applications of the language. After the fundamentals of the language, you will learn how to apply the object-oriented programming features of Kotlin 1.1. Programming with Lambdas will show you how to use the functional power of Kotlin. This book has recipes that will get you started with Android programming with Kotlin 1.1, providing quick solutions to common problems encountered during Android app development. You will also be taken through recipes that will teach you microservice and concurrent programming with Kotlin. Going forward, you will learn to test and secure your applications with Kotlin. Finally, this book supplies recipes that will help you migrate your Java code to Kotlin and will help ensure that it's interoperable with Java.
Table of Contents (21 chapters)
Title Page
Copyright and Credits
Packt Upsell

Working with interfaces in Kotlin

Interfaces in OOP are like the contract. They define the behavior or rules. The classes that implement them need to do so in order to conform to the behavior defined by interfaces. However, that's not it. Interfaces in Kotlin provide much more. Prior to Java 8, we couldn't have the implementation of methods in the interfaces, but in Kotlin, we can have that too! In this recipe, we will see how to deal with interfaces in Kotlin.

Getting ready

I'll be using IntelliJ IDEA for writing and executing code. You are free to use any IDE where you can run the Kotlin code.

How to do it…

As we have just discussed, interfaces in Kotlin can have the implementation of methods; let's follow these mentioned steps to check that out:

  1. Let's create an interface named DemoInterface:
interface DemoInterface {

    fun implementatedMethod() {
        println("From demo interface")

Defining a method with implementation in the interface is just like you would do inside a class.

  1. Now...