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Kotlin Programming Cookbook

You're reading from   Kotlin Programming Cookbook Explore more than 100 recipes that show how to build robust mobile and web applications with Kotlin, Spring Boot, and Android

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Product type Paperback
Published in Jan 2018
Publisher
ISBN-13 9781788472142
Length 434 pages
Edition 1st Edition
Languages
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Authors (2):
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Aanand Shekhar Roy Aanand Shekhar Roy
Author Profile Icon Aanand Shekhar Roy
Aanand Shekhar Roy
Rashi Karanpuria Rashi Karanpuria
Author Profile Icon Rashi Karanpuria
Rashi Karanpuria
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Toc

Table of Contents (16) Chapters Close

Preface 1. Installation and Working with Environment FREE CHAPTER 2. Control Flow 3. Classes and Objects 4. Functions 5. Object-Oriented Programming 6. Collections Framework 7. Handling File Operations in Kotlin 8. Anko Commons and Extension Function 9. Anko Layouts 10. Databases and Dependency Injection 11. Networking and Concurrency 12. Lambdas and Delegates 13. Testing 14. Web Services with Kotlin 15. Other Books You May Enjoy

Creating a chain of multiple lets in Kotlin

let is a pretty useful function provided by Kotlin's Standard.kt library. It is basically a scoping function that allows you declare the variable in its scope. Let's take a look at the given code:

someVariable.let{
// someVariable is present as "it"
}

However, the best thing is that it can be used to avoid null checks. Earlier, you might have used the following:

if(someVariable!=null){
// do something
}

While the preceding code is good, it's not very suited for mutating properties. The alternative is to use ?.let (someVariable.?let{}), which ensures that the code block runs when the variable is not null. However, what if we have multiple if-not-null chains? Let's see how to deal with those cases in this recipe.

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