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 download a file in Kotlin


We often need to download files in our Android application. The most basic way of doing this will be opening a URL connection and using InputStream to read the content of the file and storing it in a local file using FileOutputStream; all this is in a background thread using AsyncTask. However, we don’t want to reinvent the wheel. There are a lot of libraries out there that handle all this stuff very nicely for us and make our work super easy, helping us create clean code.

We can use Volley (https://developer.android.com/training/volley/index.html), a networking library by developers at Google, which makes network communication very easy and fast. Another one we can use is OkHttp (by Square), which is very efficient, and we can use it along with Retrofit (for HTTP API).

For this recipe, we will be using a networking library called Fuel, which is written in Kotlin.

Getting ready

Create a new Android project and add an activity. Now, add fuel dependencies to your...