Kotlin List.chunked() – Examples

Kotlin List.chunked()

The List.chunked() function in Kotlin is used to split a list into chunks of a specified size, creating a list of lists.

Syntax

fun <T> Iterable<T>.chunked(size: Int, transform: (List<T>) -> R): List<R>

The function takes a size parameter, representing the size of each chunk, and an optional transform function that can be applied to each chunk.

Parameter	Description
size	The size of each chunk.
transform	Optional. A function that can be applied to each chunk.

T is the type of elements in the list.

Example 1: Basic Chunking using List.chunked()

Split a list of numbers into chunks of size 3.

Kotlin Program

fun main() {
    val numbers = (1..10).toList()
    val chunkedNumbers = numbers.chunked(3)

    println(chunkedNumbers)
}

Output

[[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]]

This example uses the chunked function to split a list of numbers into chunks of size 3.

Example 2: Applying Transform using List.chunked()

Split a list of names into chunks of size 2 and convert each chunk to uppercase.

Kotlin Program

fun main() {
    val names = listOf("Alice", "Bob", "Charlie", "David", "Eva", "Frank")
    val chunkedNames = names.chunked(2) { it.map(String::toUpperCase) }

    println(chunkedNames)
}

Output

[[ALICE, BOB], [CHARLIE, DAVID], [EVA, FRANK]]

This example uses the chunked function with a transform to split a list of names into chunks of size 2 and convert each name to uppercase.

Summary

In this tutorial, we learned about Kotlin List.chunked() function with syntax and examples.