Kotlin Standard Library Cookbook

Getting ready

The basic Lazy delegate initialized using the lazy() function provided by the standard library gives the desired possibility of declaring a property of a non-null type, which can only be instantiated after a certain lifecycle event. For example, we reference an element of a screen layout in a property only after the layout was set up inside the Activity.onCreate() hook function.

However, such an implementation using Lazy will cause a memory leak if the property holds a reference to the Activity instance internally, as it will not allow it to be deleted by a garbage collector. The reason for this is that the lazy delegate is caching the instance it's holding. We are going to implement our own property delegate, called LifeCycleAwareLazy ...