Concatenate integers to a string in Kotlin

This article explores different ways to concatenate integers to a string in Kotlin.

1. Using String templates

An elegant and concise solution to concatenate multiple integers to a string is using String templates in Kotlin. A template expression starts with a dollar sign ($) and consists of a name or an expression:

fun main() {

val a = 5

val b = 2

val c = 4

val s = "$a$b$c"

println(s) // 524

}

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2. Using String concat (+)

Another option is to use the String concat operator + to concatenate integers to a string. This is demonstrated below using an empty string literal (or valueOf() function):

fun main() {

val a = 5

val b = 2

val c = 4

val s = "" + a + b + c // a.toString() + b + c

println(s) // 524

}

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3. Using `joinToString()` function

To concatenate multiple integers to a string, it is useful to create a utility function that accepts a vararg. The joinToString() function can join all vararg elements using a separator and transform function (to convert each integer to a string).

fun concatenate(vararg digits: Int): String {

return digits.joinToString(separator = "", transform = Int::toString)

}

fun main() {

val a = 5

val b = 2

val c = 4

val s = concatenate(a, b, c)

println(s) // 524

}

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4. Using `String.format()` function

Finally, we can use the String.format() function to get the formatted string from the specified integer arguments with the %s format specifier.

fun main() {

val a = 5

val b = 2

val c = 4

val s = String.format("%s%s%s", a, b, c)

println(s) // 524

}

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That’s all about concatenating integers to a string in Kotlin.

Concatenate integers to a string in Kotlin

1. Using String templates﻿

2. Using String concat (+)

3. Using joinToString() function

4. Using String.format() function

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1. Using String templates

3. Using `joinToString()` function

4. Using `String.format()` function