Remove punctuation from a string in Kotlin

This article explores different ways to remove punctuation from a string in Kotlin.

The replace() function removes each substring of the char sequence that matches the given regular expression. We can either use the POSIX class \p{Punct} or predefined punctuation class p{IsPunctuation} for creating a regular expression that matches with the ASCII punctuation characters.

fun removePunctuations(source: String): String {

return source.replace("\\p{Punct}".toRegex(), "")

}

fun main() {

var source = "(A,B)#C:{A_B}[D]"

source = removePunctuations(source)

println(source) // ABCABD

}

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The punctuation class matches with the characters !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~. We can also directly add or remove the desired characters from it.

fun removePunctuations(source: String): String {

return source.replace("[!\"#$%&'()*+,-./:;<=>?@\\[\\]^_`{|}~]".toRegex(), "")

}

fun main() {

var source = "(A,B)#C:::{A_B}[D]"

source = removePunctuations(source)

println(source) // ABCABD

}

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We can easily add another POSIX class to the regex, as shown below:

fun removePunctuations(source: String): String {

return source.replace("\\p{Punct}|\\p{Space}".toRegex(), "")

}

fun main() {

var source = "(A,B)#C: {A_B}[D]"

source = removePunctuations(source)

println(source) // ABCABD

}

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If the replace() function is frequently invoked, consider compiling the regular expression to get better performance. This can be implemented as follows in Kotlin.

import java.util.regex.Pattern

private val PUNCT_SYMBOLS = Pattern.compile("[!\"#$%&'()*+,-./:;<=>?@\\[\\]^_`{|}~]")

fun removePunctuations(source: String?): String {

return PUNCT_SYMBOLS.matcher(source).replaceAll("")

}

fun main() {

var source = "(A,B)#C:::{A_B}[D]"

source = removePunctuations(source)

println(source) // ABCABD

}

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That’s all about removing punctuation from a string in Kotlin.

Remove punctuation from a string in Kotlin

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