kotlin-stdlib/kotlin.properties/Delegates/notNull

notNull

fun <T : Any> notNull(): ReadWriteProperty<Any?, T>(source)

Returns a property delegate for a read/write property with a non-null value that is initialized not during object construction time but at a later time. Trying to read the property before the initial value has been assigned results in an exception.

Since Kotlin

1.0

Samples

import kotlin.properties.Delegates
import kotlin.test.*

fun main() { 
   //sampleStart 
   var max: Int by Delegates.notNull()

// println(max) // will fail with IllegalStateException

max = 10
println(max) // 10 
   //sampleEnd
}