Nullability

The concept of nullability in Kotlin — nullable and non-nullable types, along with the safe-call, elvis and bang-bang operators.

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THE CURRENT VERSION OF THIS ARTICLE IS PUBLISHED HERE.

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Tags: #KOTLIN FEATURE #EXERCISE

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.

The purpose of nullable types is to explicitly designate places where null values are allowed. This has two benefits:

1. the compiler forces us to deal with potential null values and prevent NPE's
2. the compiler guarantees that expressions of a non-nullable type cannot be null, saving us from writing inordinate amounts of defensive code everywhere