Kotlin Tutorials

Kotlin Set elementAtOrElse()
Syntax & Examples

Set.elementAtOrElse() extension function

The elementAtOrElse() extension function for sets in Kotlin returns an element at the given index or the result of calling the defaultValue function if the index is out of bounds of the set.

Syntax of Set.elementAtOrElse()

The syntax of Set.elementAtOrElse() extension function is:

fun <T> Set<T>.elementAtOrElse(index: Int, defaultValue: (Int) -> T): T

This elementAtOrElse() extension function of Set returns an element at the given index or the result of calling the defaultValue function if the index is out of bounds of this set.

Parameters

ParameterOptional/RequiredDescription
indexrequiredThe index of the element to return.
defaultValuerequiredA function that takes an out-of-bounds index and returns a default value.

Return Type

Set.elementAtOrElse() returns value of type T.


✐ Examples

1 Using elementAtOrElse() to get an element at a specific index or a default value

In Kotlin, we can use the elementAtOrElse() function to get an element at a specific index in a set of integers or return a default value if the index is out of bounds.

For example,

  1. Create a set of integers.
  2. Use the elementAtOrElse() function to get the element at index 2 or return -1 if the index is out of bounds.
  3. Print the result to the console using the println function.

Kotlin Program

fun main(args: Array<String>) {
    val numbers = setOf(1, 2, 3, 4, 5)
    val element = numbers.elementAtOrElse(2) { -1 }
    println("Element at index 2: $element")
}

Output

Element at index 2: 3

2 Using elementAtOrElse() with a set of strings

In Kotlin, we can use the elementAtOrElse() function to get an element at a specific index in a set of strings or return a default value if the index is out of bounds.

For example,

  1. Create a set of strings.
  2. Use the elementAtOrElse() function to get the element at index 5 or return "unknown" if the index is out of bounds.
  3. Print the result to the console using the println function.

Kotlin Program

fun main(args: Array<String>) {
    val fruits = setOf("apple", "banana", "cherry", "date")
    val element = fruits.elementAtOrElse(5) { "unknown" }
    println("Element at index 5: $element")
}

Output

Element at index 5: unknown

3 Using elementAtOrElse() with an empty set

In Kotlin, we can use the elementAtOrElse() function on an empty set to return a default value if the index is out of bounds.

For example,

  1. Create an empty set of integers.
  2. Use the elementAtOrElse() function to get the element at index 0 or return -1 if the index is out of bounds.
  3. Print the result to the console using the println function.

Kotlin Program

fun main(args: Array<String>) {
    val emptySet = emptySet<Int>()
    val element = emptySet.elementAtOrElse(0) { -1 }
    println("Element at index 0 in empty set: $element")
}

Output

Element at index 0 in empty set: -1

Summary

In this Kotlin tutorial, we learned about elementAtOrElse() extension function of Set: the syntax and few working examples with output and detailed explanation for each example.