Careeroza

let

Null Checks with ?.let

?.let { } runs the block only when the value is not null. Inside, it is a non-null type. Combine with ?: for the null case.

Example

fun sendOtp(phone: String?) {
    phone?.let { println("OTP sent to ${it.takeLast(4).padStart(10, '*')}") }
        ?: println("No phone number on file")
}

fun main() {
    sendOtp("9876543210")
    sendOtp(null)

    val length = "Kotlin".let { word ->
        println("Measuring $word")
        word.length
    }
    println(length)
}

Output

OTP sent to ******3210
No phone number on file
Measuring Kotlin
6