Kotlin – Convert String to Int

Convert string to int in Kotlin

To convert a given string value to an integer value in Kotlin, you can use String.toInt() function.

Call toInt() function on the string value str.

str.toInt()

The function returns an integer value created from the content in String value.

Examples

Convert the string “6523” to integer

In the following program, we take a string value in str variable, where the content can be an integer. We convert this string value to an integer value.

Kotlin Program

fun main() {
    val str = "6523"
    val num = str.toInt()
    println(num)
}

Output

6523

NumberFormatException if the string is not convertible to an int

If the given string is not convertible to an integer value, then toInt() function throws NumberFormatException as shown in the following program.

Kotlin Program

fun main() {
    val str = "6523 apples"
    val num = str.toInt()
    println(num)
}

Output

Exception in thread "main" java.lang.NumberFormatException: For input string: "6523 apples"
	at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.base/java.lang.Integer.parseInt(Integer.java:652)
	at java.base/java.lang.Integer.parseInt(Integer.java:770)
	at MainKt.main(main.kt:3)
	at MainKt.main(main.kt)