Some way to reverse string chars by using Kotlin language

charReversed.kt

/**
 * Kotlin code challenges. Find related objects
 * playgound: https://pl.kotl.in/NvjzuL7se
 */

import java.util.*
import kotlin.collections.ArrayList

fun main() {
    val message = "Hello, world!"
    
    println("Original: $message \n")
    println("1) ${kotlinReverse(message)}")
    println("2) ${String(optimisedArrayReverse(message.toCharArray()))}")
    println("3) ${String(arrayReverseByStack(message.toCharArray()))}")
}

fun kotlinReverse(sentence: String): String {
    return sentence.reversed()
}

fun arrayReverseByStack(chars: CharArray): CharArray {
    val length = chars.size - 1
    val stackChars = Stack<Char>()
    val reversedList: ArrayList<Char> = arrayListOf()
    
    for (char in chars) {
        stackChars.push(char)
    }
    
    while (!stackChars.empty()) {
        reversedList.add(stackChars.pop())
    }
    
    return reversedList.toCharArray()
}

fun optimisedArrayReverse(chars: CharArray): CharArray {
    val reversedChars = chars
    
    val length = chars.size
    val center = (length / 2) - 1
    var reversedIndex = chars.lastIndex
    
    if (center < 0) {
        return reversedChars
    }
    
    for (index in 0..center) {
        val temp = reversedChars[index]
        reversedChars[index] = chars[reversedIndex]
        reversedChars[reversedIndex] = temp
        
        reversedIndex -= 1
    }
    
    return reversedChars
}