Check whether a list is empty in Kotlin

This post will discuss different ways to check whether a list is empty in Kotlin. A list is empty if and only if it contains no elements.

1. Using `isEmpty()/isNotEmpty()` function

A simple solution to check for an empty list in Kotlin is using the isEmpty() function. Its usage is demonstrated below:

fun main() {

val list = listOf<String?>()

if (list == null) {

println("List is null")

}

if (list.isEmpty()) {

println("List is empty")

} else {

println("List is not empty or null")

}

Instead of checking separately if the list is null or empty, you can combine the isEmpty() function with the null check:

fun main() {

val list = listOf('A', 'B', 'C')

if (list == null || list.isEmpty()) {

println("List is either empty or null")

}

Or, do inverse using the isNotEmpty() function:

fun main() {

val list = listOf('A', 'B', 'C')

if (list != null && list.isNotEmpty()) {

println("List is not empty")

}

Another solution is to use the size property or the count() function, both return the number of elements in the collection.

fun main() {

val list = listOf('A', 'B', 'C')

if (list != null && list.size > 0) {

println("List is not empty")

} else {

println("List is either empty or null")

}

That’s all about checking whether a list is empty in Kotlin.