Lateinit

An explanation of, and motivation for, lateinit

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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.

Normally, properties declared as having a non-null type must be initialized by the constructor. However, it is often the case that doing so is not convenient. For example, properties can be initialized through dependency injection, or in the setup method of a unit test. In these cases, you cannot supply a non-null initializer in the constructor, but you still want to avoid null checks when referencing the property inside the body of a class. This is precisely the situation lateinit was designed to solve.