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

How to type check an object

One often needs to check if an object is of a particular type at runtime. With Java, we used an instance of a keyword; with Kotlin, it is the is keyword.

Getting ready

You need to install a preferred development environment that compiles and runs Kotlin. You can also use the command line for the purpose, for which you need Kotlin compiler installed along with JDK. I am using online IDE at to compile and run my Kotlin code for this recipe.

How to do it...

Let's see how to type check an object in these steps:

  1. Let's try a very basic example, trying is with string and integer. In this example, we will type check a string and an integer:
fun main(args: Array<String>) {
    var a : Any = 1
    var b : Any = "1"
    if (a is String) {
        println("a = $a is String")
    else {
        println("a = $a is not String")
    if (b is String) {
        println("b = $b is String")
    else {
        println("b = $b is not String...