How can I call a parent method from a companion object in kotlin

Question

I have a Super class:

open class A {
    fun doStuff() {

    }
}

and then I have a sub Class which extends that:

class B: A() {
   companion object {
        doStuff() //compile error
   }
}

How can I call my doStuff() method from the companion object?

Answer 1

You can't.

The companion object is a rough equivalent of the static keyword in Java. The doStuff() function of class A(and its subclasses) can only be called from an actual object of that class (like A().doStuff() or B().doStuff())

When trying to call that function from B's companion object, there is no such object of A (or B) on which you could call that function, since you're in a static context.

If you'd write the Java equivalent of what you posted, you'd receive the error

non-static method cannot be referenced from a static context

which is more descriptive than what you're probably getting from Kotlin's compiler and is well explained here.