Late initialisation in Kotlin
Non-null type properties must be initialised in the constructor but that’s not always very convenient. lateinit properties change that.
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private lateinit var name: String
fun getMessage(): String {
name = "RealKotlin"
val message = "We didn't even need to say $name until now"
// lateinit properties are always mutable. Be careful!
name = "42"
return message
}
fun getNewMessage(): String = name
fun main(args: Array<String>) {
println(getMessage())
// We didn't even need to say RealKotlin until now
println(getNewMessage())
// 42
}
Whenever you need a mutable property or one that is set outside of your class, lateinit may be just what you need.