Apply a function to each element of a List in Kotlin

This article explores different ways to apply a function to each element of a List in Kotlin.

1. Using `map()` function

The standard approach to apply a given function to the elements of the list is using the map() function. This solution should be used to get a new list, leaving the original list unchanged.

fun main() {

val words = listOf("A", "B", "C", "D")

val caps = words.map { it.toLowerCase() }

println(caps)

}

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Output:

[a, b, c, d]

2. Using `replaceAll()` function

If you need to in-place transform a list, consider using the replaceAll() function instead of map(). The replaceAll() function can apply a specified function to each element of the list, as shown below:

fun main() {

val words = mutableListOf("A", "B", "C", "D")

words.replaceAll { it.toLowerCase() }

println(words)

}

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Output:

[a, b, c, d]

3. Using Loop

You can also write our own routine for this simple task. The idea is to iterate over the list using a loop, and transform each encountered element, and insert the element in a new list. This logic would translate to the following code:

fun main() {

val words = listOf("A", "B", "C", "D")

val caps: MutableList<String> = mutableListOf()

for (word in words) {

caps.add(word.toLowerCase())

}

println(caps)

}

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Output:

[a, b, c, d]

That’s all about applying a function to each element of a List in Kotlin.

Apply a function to each element of a List in Kotlin

1. Using map() function

2. Using replaceAll() function

3. Using Loop

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1. Using `map()` function

2. Using `replaceAll()` function