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This post shows how to convert a comma-separated strings (CSVs) to a list and back. In Kotlin, we can create both immutable or mutable lists.

Requirements

IntelliJ IDEA Ultimate 2016.3
- The Community Edition may be enough but we have not tried it.
Kotlin Version 1.1
Windows 10 Enterprise

CSV String to list

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package exercise01

fun main(args: Array<String>) {

    val alphabet: String = "A,B,C,B,E,F"

    val regex = "\\s*,\\s*"

    val immutableList: List<String> = alphabet.split(regex).toList()
    val mutableList = alphabet.split(regex).toMutableList()

    print("Immutable List: " + immutableList)
    print("\n")
    print("Mutable List: " +mutableList)
    mutableList.add("G")
    print("\n")
    print("Updated Mutable List: " +mutableList)

}

package exercise01

fun main(args: Array<String>) {

val alphabet: String = "A,B,C,B,E,F"

val regex = "\\s*,\\s*"

val immutableList: List<String> = alphabet.split(regex).toList()

val mutableList = alphabet.split(regex).toMutableList()

print("Immutable List: " + immutableList)

print("\n")

print("Mutable List: " +mutableList)

mutableList.add("G")

print("\n")

print("Updated Mutable List: " +mutableList)

}

Outputs:

Immutable List: [A,B,C,B,E,F]
Mutable List: [A,B,C,B,E,F]
Updated Mutable List: [A,B,C,B,E,F, G]

Immutable List: [A,B,C,B,E,F]

Mutable List: [A,B,C,B,E,F]

Updated Mutable List: [A,B,C,B,E,F, G]

List to CSV string

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package exercise01

fun main(args: Array<String>) {

    val immutableList = listOf("A", "B", "C", "D", "E", "F")

    val alphabet: String = immutableList.joinToString { e -> e }

    print(alphabet)

}