Kotlin List.component1() – Examples

Kotlin List.component1()

The Kotlin List.component1() function returns first element from the list.

Syntax

List.component1()

Example 1

In this example,

  1. Take a list with one or more elements.
  2. Call component1() function on the list. The function should return the first element.

Program

fun main(args: Array<String>) {
    val list1 = listOf("a", "b", "c")
    val result = list1.component1()
    print(result)
}

Output

a

Example 2

In this example,

  1. Take an empty list, i.e., List with no elements.
  2. Call component1() function on the list. As there no at least one element in the list, the function should throw java.lang.ArrayIndexOutOfBoundsException.

Program

fun main(args: Array<String>) {
    val list1 = listOf<String>()
    val result = list1.component1()
    print(result)
}

Output

Exception in thread "main" java.lang.IndexOutOfBoundsException: Empty list doesn't contain element at index 0.
	at kotlin.collections.EmptyList.get(Collections.kt:35)
	at kotlin.collections.EmptyList.get(Collections.kt:23)
	at KotlinExampleKt.main(KotlinExample.kt:3)