Kotlin String - toDoubleOrNull() Function

The Kotlin string toDoubleOrNull() function is used to convert or parse the string as a double (a floating-point number) and returns the result. If the string is not converted or not a valid representation of a number then it will return null.

Syntax

Following is the syntax of the Kotlin string toDoubleOrNull() function −

fun String.toDoubleOrNull(): Int?

Parameters

This function does not accepts any parameters.

Return value

This function returns a double value if the string a valid floating-point number. Otherwise; null.

Example 1: Convert a Number String into Double

Following is the basic example of converting a number string to a double value using the toDoubleOrNull() function −

fun main() {
   val number_str = "102510"
   val int_num = number_str.toDoubleOrNull()
   println("Double Value: " + int_num)
}

Output

Following is the output −

Double Value: 102510.0

Example 2: If a String is not a Valid Number String

Let's see another example of the toDoubleOrNull() function. If the string is not a valid number it will return null −

fun main() {
   val String = "1234abc"
   // conver string to Double
   val Number = String.toDoubleOrNull()
   println("Double Value:" + Number)
}

Output

Following is the output −

Double Value:null

Example 3: Use Conditional Statement

In this example, we use the toDoubleOrNull() function and handling nullable result using the if-else statement −

fun main() {
   val input = "456.78"
   // convert to double
   val result = input.toDoubleOrNull()
   if (result != null) {
      println("Converted to double: $result")
   } else {
      println("Invalid number!")
   }
}

Output

Following is the output −

Converted to double: 456.78