CODEWITHSUNDEEP
javaclasskotlin
John Carpenter
John Carpenter

Reputation: 33

Static final field inheritance in kotlin

I have a really simple question here, but can't figure it out. Consider a java class:

class A {
    public static final int AA=5;
}

which translates (internally) into kotlin as this:

open class A {
    companion object {
        val AA:Int=5
    }
}

At least that's what I assume. Now if you inherit in java:

class B extends A {
    int AAA;
}

you can access field AA (from A) through B like this: B.AA . However, in Kotlin it's impossible. The only way to access it is through A.AA. Is this a built-in feature or I am doing something wrong?

Upvotes: 2

Views: 540

Answers (1)

Alexey Romanov
Alexey Romanov

Reputation: 170745

In Java, when the compiler sees B.AA, it automatically transforms it into A.AA. There's no real inheritance or overriding there.

Kotlin's developers decided not to emulate this feature, because it doesn't fit with thinking of static methods as belonging to an object: the companion object of B doesn't extend the companion object of A, and can't because you can't extend an object.

Note that similarly, in Java you can access the field via a.AA where a is an instance of A; you can't do that in Kotlin either.

Upvotes: 3

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