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
Contributors
Preface
Index

Sorting a list by specified comparator


Sorting a list is one of the most common operations done on the list. When we try to sort a list of custom objects, we need to specify the comparator. Let's see how we can sort a list by the specified comparator.

Getting ready

I'll be using IntelliJ IDEA for writing and running Kotlin code; you are free to use any IDE that can do the same task.

How to do it…

In the following examples, we will try to sort objects based on certain properties. This will give us an idea of how to sort based on the specified comparator:

  1. Let's create a Person class with age property. We will be sorting a list of person objects based on age:
fun main(args: Array<String>) {
    val p1=Person(91)
    val p2=Person(10)
    val p3=Person(78)
    val listOfPerson= listOf(p1,p2,p3)
    var sortedListOfPerson=listOfPerson.sortedBy {
        it.age
    }
}
class Person(var age:Int)
  1. To sort a list based on the specified comparator, we need to use the sortedBy function:
fun main(args...