Collection Operations: Filtering

An introduction to the most important filtering operations: filter, take, drop, slice, distinct, and their variants.

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THE CURRENT VERSION OF THIS ARTICLE IS PUBLISHED HERE.

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Tags: #FYI++

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.

Filtering

filter

inline fun <T> Iterable<T>.filter(
    predicate: (T) -> Boolean
): List<T>

Probably the most ubiquitous of all filtering functions, filter accepts a predicate and returns a List of all the elements for which the predicate returns true.

Example