How to convert String to Int in Kotlin?

Question

I am working on a console application in Kotlin where I accept multiple arguments in main() function

fun main(args: Array<String>) {     // validation & String to Integer conversion } 

I want to check whether the String is a valid integer and convert the same or else I have to throw some exception.

How can I resolve this?

Answer 1

You could call toInt() on your String instances:

fun main(args: Array<String>) {     for (str in args) {         try {             val parsedInt = str.toInt()             println("The parsed int is $parsedInt")         } catch (nfe: NumberFormatException) {             // not a valid int         }     } } 

Or toIntOrNull() as an alternative:

for (str in args) {     val parsedInt = str.toIntOrNull()     if (parsedInt != null) {         println("The parsed int is $parsedInt")     } else {         // not a valid int     } } 

If you don't care about the invalid values, then you could combine toIntOrNull() with the safe call operator and a scope function, for example:

for (str in args) {     str.toIntOrNull()?.let {         println("The parsed int is $it")     } }