Remove duplicate adjacent whitespaces from a string in Kotlin

This article explores different ways to remove duplicate adjacent whitespaces from a string in Kotlin.

Since Strings are immutable in Kotlin, we can’t remove whitespaces from it. However, we can create a new string with duplicate whitespaces removed. To replace all consecutive whitespaces with a single space ' ', use the replace() function with regex \s+. The regular expression \s+ matches with one or more whitespace characters.

fun main() {

val s = "Example Text"

val filtered = s.replace("\\s+".toRegex(), " ")

println(filtered) // Example Text

}

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To remove whitespaces from the beginning and end of the string, call the trim() function before calling the replace() function.

fun main() {

val s = " Example Text "

val filtered = s.trim().replace("\\s+".toRegex(), " ")

println(filtered) // Example Text

}

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Alternatively, use the regex \s{2,} which matches with exactly two or more whitespace characters.

fun main() {

val s = " Example Text "

val filtered = s.trim().replace("\\s{2,}".toRegex(), " ")

println(filtered) // Example Text

}

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If the replace() function is called multiple times, it is recommended to compile the regular expression and invoke the replaceAll() function on the matcher.

import java.util.regex.Pattern

private val pattern = Pattern.compile("\\s{2,}")

fun main() {

val s = " Example Text "

val filtered = pattern.matcher(s).replaceAll(" ")

println(filtered) // Example Text

}

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Finally, if we need to remove all whitespaces from the string, use the filterNot() function with the isWhitespace() function as the predicate (or filter() function with the reverse predicate).

fun main() {

val s = " Some Text "

val filtered = s.filterNot { it.isWhitespace() }

println(filtered) // SomeText

}

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That’s all about removing duplicate adjacent whitespaces from a string in Kotlin.

Remove duplicate adjacent whitespaces from a string in Kotlin

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