Programming Kotlin

Late initialization

Any non-null property has to be initialized in the constructor. What if you want to inject the property value via a dependency injection and you don't want to check for null every time you access it? Or, maybe you simply set the property value in one of the methods exposed by your type. Kotlin comes with support for delayed initialization. All you have to do is use the lateinit keyword:

 class Container { lateinit var delayedInitProperty: DelayedInstance fun initProperty(instance: DelayedInstance): Unit { this.delayedInitProperty = instance } } class DelayedInstance (val number:Int) ... val container= Container() container.initProperty(DelayedInstance(10)) println("with delayed initialization:Number=${container.delayedInitProperty.number}") ...