When Construct

Demonstrating the when construct, with a quick note on smart casting and expressions vs. statements.

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THE CURRENT VERSION OF THIS ARTICLE IS PUBLISHED HERE.

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Tags: #KOTLIN FEATURE

This article is part of the Kotlin Primer, an opinionated guide to the Kotlin language, which is indented to help facilitate Kotlin adoption inside Java-centric organizations. It was originally written as an organizational learning resource for Etnetera a.s. and I would like to express my sincere gratitude for their support.

It is recommended to read the Introduction before moving on. Check out the Table of Contents for all articles.

Instead of the widely used switch statement, Kotlin provides the more flexible and clear when construct. It can be used both as a statement and as an expression.

Expressions vs. Statements

What is and isn’t an expression/statement depends on the language.

A simple way of understanding the difference between expressions and statements is this: