Difference between open and override methods in Kotlin?

Question

open class Base {

    open fun v() {}

    fun nv() {}
}

class Derived() : Base() {

    override fun v() {}
}

This is an example. Can someone please

Answer 1

By default, the functions in Kotlin are defined as final. That means you cannot override them. If you remove the open from your function v() than you will get an error in your class Derived that the function v is final and cannot be overridden.

When you mark a function with open, it is not longer final and you can override it in derived classes.