Kotlin List forEachIndexed()
Syntax & Examples

Syntax of List.forEachIndexed()

The syntax of List.forEachIndexed() extension function is:

fun <T> Iterable<T>.forEachIndexed( action: (index: Int, T) -> Unit)

This forEachIndexed() extension function of List performs the given action on each element, providing sequential index with the element.

✐ Examples

1 Example

In this example,

We create a list of integers named list1.
We use the forEachIndexed() function on list1 to print each element with its index to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list1 = listOf(1, 2, 3, 4, 5)
    list1.forEachIndexed { index, value -> println("Index: \$index, Value: \$value") }
}

Output

Index: 0, Value: 1
Index: 1, Value: 2
Index: 2, Value: 3
Index: 3, Value: 4
Index: 4, Value: 5

2 Example

In this example,

We create a list of characters named list2.
We use the forEachIndexed() function on list2 to print each element with its index to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list2 = listOf('a', 'b', 'c')
    list2.forEachIndexed { index, value -> println("Index: \$index, Value: \$value") }
}

Output

Index: 0, Value: a
Index: 1, Value: b
Index: 2, Value: c

3 Example

In this example,

We create a list of strings named list3.
We use the forEachIndexed() function on list3 to print each element with its index to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list3 = listOf("apple", "banana", "cherry")
    list3.forEachIndexed { index, value -> println("Index: \$index, Value: \$value") }
}

Output

Index: 0, Value: apple
Index: 1, Value: banana
Index: 2, Value: cherry

Summary

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