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

Accessing views of view groups using extension functions


We can use extension functions to add new behaviors to a class that we may not even have access to. We can also add extension functions to view groups. One such view group is recycler view. Let's see how we can access views of a recycler view using extension functions.

Getting ready

I'll be using Android Studio 3 to write code. You can get started by creating a new project in Kotlin with a blank activity in Android Studio 3+, as we won't be using any code from other recipes. You also need an intermediate understanding of Android development.

How to do it…

Kotlin has some operators that we can use on a class. We will be overloading one of these operators to get views of our view group:

  1. We can access views of a view group by overloading the get operator like this:
operator fun ViewGroup.get(position: Int): View
{
    return getChildAt(position)
}
  1. Now, in order to get a view from the view group, we can use either of the following methods:
val...