How to get reference to static class of Java super class in Kotlin

Question

I've got sample third party Java code:

public class ApiClass extends PackagePrivateClass {
}

abstract class PackagePrivateClass {
    public static class StaticClass {
    }
}

So only ApiClass and StaticClass are public. In Java I can get reference to StaticClass with: ApiClass.StaticClass. For the same code in Kotlin I got Unresolved reference: StaticClass. I can't also get reference via PackagePrivateClass, because it's package private (captain obvious). Is there any hack to get reference to StaticClass (it's third party code so I can't simply make PackagePrivateClass public)?

I understand that it's probably 'by design', however it forbids me from using 3p code

Answer 1

It seems the only solution is to build Java wrapper class that your kotlin class can access to.

public class ApiClass extends PackagePrivateClass {

}

abstract class PackagePrivateClass {

    public static class StaticClass {

        void instanceFunction() {

        }

        static void classFunction() {
        }
    }
}

The adapter java class (StaticClassAdapter.java):

class StaticClassAdapter {

    private static ApiClass.StaticClass staticClass;

    void instanceFunction() {
        staticClass.instanceFunction();
    }

    static void classFunction() {
        PackagePrivateClass.StaticClass.classFunction();
    }
}

So in your kotlin code...

class KotlinClass {

    fun main() {
        StaticClassAdapter().instanceFunction()
        StaticClassAdapter.classFunction()
    }
}