Kotlin-Interfaces.kt

class MyClass(val listener: Listener) {

    interface Listener {
        fun doThis()
        fun doThat(number: Int)
    }

    fun someFunction(){
        listener.doThis()
        listener.doThat(12)
    }
}

class UserClass {
    val listener = object: MyClass.Listener {
        override fun doThis() {
            
        }

        override fun doThat(number: Int) {
            
        }
    }

    val myClass = MyClass(listener)
}