How to check string has digit only in kotlin

Question

Hey I working in kotlin android. The string is coming from server and it might be contains digit, character, empty string or null value. I want to convert that value in double because I want to compare value. So is there any better way to check that string only contain digit value and not empty or null in a kotlin way. The list is huge so I want a efficient way.

Price.kt

data class Price(
  var value: String? = null
)

main.kt

val defaultValue : Double = 4.23
val list = listOf(Price("2.33"), Price("fr23"), Price(""), Price(null), Price("4.23"), Price("12.23"))

list.forEach{
   if(it == defaultValue){
      println("Found It")
   }
}

Answer 1

Kotlin already has an efficient solution: toDoubleOrNull

Parses the string as a Double number and returns the result or null if the string is not a valid representation of a number.

if (list.any { it.value.toDobleOrNull() == defaultValue }) {
    println("Found It")
}