Hands-On Object-Oriented Programming with Kotlin

Abstract classes

An abstract class is a generic concept and it does not belong to a concrete idea. We do not create an instance of an abstract class; its only responsibility is to facilitate the creation of other classes. An abstract class is used to define which behaviors a class should have instead of how it should be implemented. Take a look at the following example from the previous section:

open class Person (val fName: String, var lName: String, var pAge: Int) {      fun speak() {         println("My name is $fName $lName age is $pAge")     }    fun greet() {         println("Hi there...$fName ")     } } class Student(fName: String, lName: String, pAge: Int , val studentId : String) : Person(fName,lName,pAge) { ... ...}

Notice that the Person class is a normal class ...