Merge elements of a Collection separated by a delimiter in Kotlin

This article explores different ways to construct a new string from elements of a collection separated by the specified delimiter in Kotlin.

1. Using `StringBuilder` class

The idea is to iterate over the given collection and build a string out of each encountered element separated with the delimiter using a StringBuilder.

fun mergeElements(collection: Collection<String>, separator: String): String {

val sb = StringBuilder()

collection.map { sb.append(it).append(separator) }

return sb.removeSuffix(separator).toString()

}

fun main() {

val collection: Collection<String> = listOf("I", "love", "Kotlin")

val separator = "-";

val str = mergeElements(collection, separator)

println(str) // Kotlin-Rocks

}

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2. Using `StringJoiner` class

Alternatively, you can use the StringJoiner class, whose constructor accepts a separator. To append elements to it, you can use the add() function.

fun mergeElements(collection: Collection<String>, separator: String): String {

val sj = java.util.StringJoiner(separator)

collection.map { sj.add(it) }

return sj.toString()

}

fun main() {

val collection: Collection<String> = listOf("Kotlin", "Rocks")

val separator = "-";

val str = mergeElements(collection, separator)

println(str) // Kotlin-Rocks

}

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3. Using `String.join()` function

Another plausible way is to use the join() function provided by the StringJoiner class, which takes a delimiter and joins elements of the specified collection together with it.

fun mergeElements(collection: Collection<String>, separator: String): String {

return java.lang.String.join(separator, collection)

}

fun main() {

val collection: Collection<String> = listOf("Kotlin", "Rocks")

val separator = "-";

val str = mergeElements(collection, separator)

println(str) // Kotlin-Rocks

}

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That’s all about merging elements of a Collection separated by a delimiter in Kotlin.

Merge elements of a Collection separated by a delimiter in Kotlin

1. Using StringBuilder class

2. Using StringJoiner class

3. Using String.join() function

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1. Using `StringBuilder` class

2. Using `StringJoiner` class

3. Using `String.join()` function