Generate a random character in Kotlin

This article explores different ways to generate a random character in Kotlin.

1. Using `CharRange.random()` function

To generate a random element between a specific range of characters, call the random() function on the Kotlin CharRange. For instance, the following code generates a random character in the range A-Z.

fun main() {

val rand = ('A'..'Z').random()

println(rand)

}

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Don’t call random() function on an empty range, otherwise IllegalArgumentException is thrown. We can easily extend the solution to generate a random character in the alphanumeric range. The alphanumeric range consists of digits, lowercase, and uppercase characters.

fun main() {

val rand = listOf(('0'..'9'), ('a'..'z'), ('A'..'Z')).flatten().random()

println(rand)

}

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2. Using `Random.nextInt()` function

Alternatively, use the nextInt() function from the kotlin.random.Random class to generate a random character between some specific character range, as shown below.

import kotlin.random.Random

fun randomChar(): Char {

return (Random.nextInt(26) + 'A'.toInt()).toChar()

}

fun main() {

val rand = randomChar()

println(rand)

}

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To generate a random value from the lowercase and uppercase characters range, do like:

import kotlin.random.Random

fun randomChar(): Char {

val rand = Random.nextInt(52)

val base = if (rand < 26) 'A' else 'a'

return (base.toInt() + rand % 26).toChar()

}

fun main() {

val rand = randomChar()

println(rand)

}

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Finally, to generate a random character using any custom character set, do as follows.

import kotlin.random.Random

fun randomChar(chars: String): Char {

return chars[Random.nextInt(chars.length)]

}

fun main() {

val chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

val rand = randomChar(chars)

println(rand)

}

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That’s all about generating a random character in Kotlin.

Generate a random character in Kotlin

1. Using CharRange.random() function

2. Using Random.nextInt() function

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1. Using `CharRange.random()` function

2. Using `Random.nextInt()` function