Google just recently announced official support for Kotlin in Android so we can now take advantage of techniques to enhance the development experience with ArcGIS Android. One way we can do this is through the use of Kotlin Android Extensions.
Accessing View Resources
In Android Java, once you provide resources in your app, e.g. a MapView, you can apply it by referencing its resource ID which are defined in your projects R class that is automatically generated. You can access resources in code by passing a resource ID as a method parameter. For example, you can access a MapView using findViewById:
MapView mapView = (MapView) findViewById(R.id.mapView);