In this article you will examine various techniques to find out whether a string is numeric or not in Kotlin.

Method 1: Check if a string is numeric or not using regular expressions (regex)

fun main(args: Array<String>) {

    val string = "-1234.15"
    var numeric = true

    numeric = string.matches("-?\\d+(\\.\\d+)?".toRegex())

    if (numeric)
        println("$string is a number")
    else
        println("$string is not a number")
}

Result

-1234.15 is a number

Method 2: Check if a string is numeric

import java.lang.Double.parseDouble

fun main(args: Array<String>) {

    val string = "12345s15"
    var numeric = true

    try {
        val num = parseDouble(string)
    } catch (e: NumberFormatException) {
        numeric = false
    }

    if (numeric)
        println("$string is a number")
    else
        println("$string is not a number")
}

Result

12345.15 is a number