Iterate list in reverse order in Kotlin

This post will discuss various ways to iterate a list in Kotlin in reverse order without actually reversing the list.

1. Using `toString()` function

If you want to display the contents of the list in reverse order, you can get a reversed read-only view of the original List using the asReversed() function and then print its string representation using the toString() function.

fun main() {

val list: List<String> = listOf("One", "Two", "Three")

println(list.asReversed().toString())

}

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2. Using ListIterator

You can use a special iterator ListIterator, that additionally allows bidirectional access over a normal iterator. It takes the starting position on the list.

fun main() {

val list = listOf("One", "Two", "Three")

// start with the end of the list

val itr: ListIterator<String> = list.listIterator(list.size)

// `hasPrevious()` returns true if the list has a previous element

while (itr.hasPrevious()) {

println(itr.previous())

}

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3. Using loop

Since List is an ordered collection, you can use index-based for-loop to access elements by their index in the list. To print the list backward, you can do like:

fun main() {

val list = listOf("One", "Two", "Three")

for (i in list.indices.reversed()) {

println(list[i])

}

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You can also call the forEach() function on the reversed read-only view of the original List to print each list element in reverse order.

fun main() {

val list: List<String> = listOf("One", "Two", "Three")

list.asReversed().forEach { println(it) }

}

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That’s all about iterating a list in reverse order in Kotlin.

Iterate list in reverse order in Kotlin

1. Using toString() function

2. Using ListIterator

3. Using loop

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1. Using `toString()` function