Kotlin / Java - Interface implementation + Inheritance

Question

I have the following classes and interface:

class A() {
    fun one() {...}
    fun two() {...}
}

class B(): A, C {
    fun tree() {...}
}

interface C {
    fun one()
    fun two()
    fun tree()
}

As you can class B extends A and also implements interface C. The problem is that in Kotlin class B which is the actual implementor of C does not have the 2 first funcs and therefore not implementing the right functions for the interface. Is there a right way to do such thing?

Answer 1

1. The A class needs to be marked open .
2. The super class A of the class B needs to be initialized (ie A() )
3. The B.tree() method requires override modifier

Apart of that, it should work...

open class A {
    fun one() {}
    fun two() {}
}

class B: A(), C {
    override fun tree() {}
}

interface C {
    fun one()
    fun two()
    fun tree()
}