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.
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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.