Instantiate Kotlin class from string

Question

I have a list of classes:

val availableClasses = listOf<Whatever>(
    classA(),
    classB(),
    classC()
)

I am randomly selecting an item from this list using:

private var selection: Whatever = availableClasses.random()

Unfortunately, I think this approach is instantiating every class included in the list when the list is loaded.

I am hoping to work around this by replacing the list of classes with a list of strings:

val availableClasses = listOf<String>(
    "classA",
    "classB",
    "classC"
)

Then once I have a selected string, instantiate only that one; something like:

private var selection: String = availableClasses.random()
// pseudo-code
val chosenClass = selection.toClass()

I can reference classes in Python using strings with the getattr function.

Is anything like this possible in Kotlin?

I'm also open to better approaches to this problem.

Answer 1

Instantiating classes by String name is more error-prone than using a constructor, because it relies on using a fully qualified, correctly spelled name, and the class having a specific constructor (either empty, or with specific arguments). So it can be done, but should be avoided when there are safer ways of doing it (ways where the compiler will give you an error if you're doing it wrong, instead of having an error occur only after you run the compiled program).

If I understand correctly, you want a list of classes that will only be instantiated one-at-a-time at random. One way to do this would be to make a list of class constructors.

val classConstructors = listOf<() -> Any>(
    ::ClassA,
    ::ClassB,
    ::ClassC
)

val randomInstantiatedClass = classConstructors.random()()