Extension function of String class

Question

I want to create an extension function of String which takes a String and returns a new String with the characters as the first, but sorted in ascending order. How can I do this? I am new to Kotlin.

Answer 1

fun String.ascending() = String(toCharArray().sortedArray())

Then:

println("14q36w25e".ascending())  // output "123456eqw"

Answer 2

Extension function for printing characters of a string in ascending order

Way 1:

fun String.sortStringAlphabetically() = toCharArray().sortedArray())

Way 2:

fun String.sortStringAlphabetically() = toCharArray().sortedArrayDescending().reversedArray()

Way 3:

fun String.sortStringAlphabetically() = toCharArray().sorted().joinToString(""))

Way 4:

fun String.sortStringAlphabetically() = toCharArray().sortedBy{ it }.joinToString(""))

Then you can use this extension function by the below code:

fun main(args: Array<String>) {
    print("41hjhfaf".sortStringAlphabetically())
}

Output: 14affhhj

Answer 3

You can combine built in extensions to do it quickly:

fun String.sortedAlphabetically() = toCharArray().apply { sort() }

First you get array of underlying characters, then you apply sort to that array and return it. You are free to cast result .toString() if You need.

Answer 4

I have one more:

fun String.inAscending(): String = toMutableList().sortedBy { it }.joinToString("")

And better:

fun String.ascending(): String = toMutableList().sorted().joinToString("")

Answer 5

In my opinion, do it in kotlin way i.e

fun String.sortAscending() = toCharArray().sortedBy{ it }.joinToString("")