Convert Integer List to IntArray in Kotlin

This article explores different ways to convert List of Integer to IntArray in Kotlin.

To convert a list of integers to an array of int, you can use the toIntArray() function.

fun main() {

val list = listOf(1, 2, 3, 4, 5)

val primitive = list.toIntArray()

println(primitive.contentToString()) // [1, 2, 3, 4, 5]

}

If your list contains the null values, you need to filter out the null values first. This can be done using the filterNotNull() function.

fun main() {

val list = listOf(1, 2, 3, 4, null, 5)

val primitive = list.filterNotNull().toIntArray()

println(primitive.contentToString()) // [1, 2, 3, 4, 5]

}

Alternatively, you can handle the null inside the lambda expression, as shown below:

fun main() {

val list = listOf(1, 2, 3, 4, null, 5)

val primitive = list.map { i: Int? -> i ?: 0 }.toIntArray()

println(primitive.contentToString()) // [1, 2, 3, 4, 5]

}

That’s all about converting an Integer list to IntArray in Kotlin.