Kotlin Extension Operators

Kotlin allows classes to be extended using Extension Functions. These Extension Functions can also be used for extending operators if they are declared with the `operator` keyword.

An example of such an Extension Function can be seen below, to draw a repeated set of characters.

operator fun Int.times(text: CharSequence): CharSequence {
    val result = StringBuilder()

    for (i in 1..this) {

    return result.toString()

fun main(args: Array<String>) {
    val line = 10 * "x"


Running the script results in the output of a line consisting of x characters:


2 Replies to “Kotlin Extension Operators”

  1. You could add example with “buildString” tip in this example 😉

    operator fun Int.times(text: CharSequence): CharSequence {
        return buildString {
            for (i in 1..this@times) {

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