Programming Kotlin

Useful KClass properties

A KClass fully describes a particular class including its type parameters, superclasses, functions, constructors, annotations, and properties. Let's define a toy class:

    class Sandwich<F1, F2>() 

Now we can inspect the KClass for this and find out the types of parameters it declares. We do this using the typeParameters property available on the KClass instance:

    val types = Sandwich::class.typeParameters 

From here, we can get the label of the type parameter, and the upper bounds, if any have been defined (otherwise Any):

    types.forEach { 
      println("Type ${it.name} has upper bound ${it.upperBounds}") 
    } 

In the case of Sandwich, this would output the following:

 Type F1 has upper bound [kotlin.Any?] Type F2 has upper bound [kotlin.Any?] ...