Kotlin List.component1() Function

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

Syntax of List.component1()

The syntax of List.component1() function is

list.component1()

Return Value

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

Example 1: Get First Element in List

In this example, we will take a list of elements of string type, and get the first element programmatically using List.component1() function.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf("ab", "bc", "cd", "de", "ef", "fg", "gh")
    val first = list1.component1()
    print("First element is : \"$first\"")
}

Output

First element is : "ab"

Example 2: List.component1() with Empty List

If you call component1() function on an empty list, the function throws java.lang.IndexOutOfBoundsException. Let us check with a Kotlin example program.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf<String>()
    val first = list1.component1()
    print("First element is : \"$first\"")
}

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 HelloWorldKt.main(HelloWorld.kt:3)

Conclusion

In this Kotlin Tutorial, we learned how to get the first element of a list, using Kotlin List.component1() function.