Hi all, sorry if this isn't the place for this, I ...

# getting-started

[James Whitehead]

Hi all, sorry if this isn't the place for this, I tried in #reflect but didn't get any responses 😞
A couple of questions with respect to reflection:
1. Is there an equivalent in Kotlin Reflect to Java's isInterface ? I see we have isAbstract , isOpen , etc, but I haven't found anything for interface.
2. Follow up question; is MyClass::class.java.interfaces the recommended way to get the interfaces implemented by a given class?

[Ivan Pavlov]

1. Looks like the only way is to use java API (I didn't found any kotlin-reflect way to do that). The first link in google shows the same answer https://stackoverflow.com/questions/48568268/how-to-distinguish-between-a-class-and-an-interface-in-kotlin-using-kclass-refle

[Ivan Pavlov]

2. In kotlin you can get supertypes or allSupertypes and process them somehow I guess

[Rob Elliot]

Is it fair to say that a class without constructors must be an interface? If so:
val KClass<*>.isInterface get() = constructors.isEmpty()
should work.

[Ivan Pavlov]

@Rob Elliot from the answer on stackoverflow

Please note that the constructors counting solution might not be very precise for general purpose use. For example, Kotlin package facade classes do not have any constructors either, but they are not interfaces (UPD: and their constructors cannot even be reflected with kotlin-reflect, just as those of anonymous classes, KFunction and maybe more).

[Rob Elliot]

Cool, thanks, should have followed the link first
edit - drat, if I’d only clicked before writing this I could have blamed it on stackoverflow being down for maintenance…

[James Whitehead]

Thanks @Ivan Pavlov, only problem with the supertypes approach is that you also get Any

[James Whitehead]

So through some experimentation with the debugger and some simple unit tests I discovered that KClass.isAbstract returns true for an interface. Which is fine for my use case, but probably not very helpful if one were trying to distinguish between a class, abstract class and an interface.