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

How to sort collection by multiple fields in Kotlin


In this recipe, we will learn how to sort a collection by multiple fields in Kotlin. This often comes in handy when we want to give precedence to an object over another object when both have equal value on a specific property. For example, we might have a list of Student objects and want to arrange them in ascending order of age, but if two students have the same age, we will order them based on their GPA. In this recipe, we will see how to handle use cases like this. So let's get started!

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…

Now, let's follow these steps to sort based on multiple fields of an object:

  1. First, let's create the Student class:
class Student(val age:Int, val GPA: Double)
  1. Then, create a list of Student objects:
val studentA=Student(11,2.0)
val studentB=Student(11,2.1)
val studentC=Student(11,1.3)
val studentD=Student(12,1.3...