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Kotlin program | Example of inheritance

Kotlin | Inheritance: Here, we are implementing a Kotlin program to demonstrate the example of inheritance.
Submitted by IncludeHelp, on June 03, 2020

Inheritance

• Inheritance is a mechanism wherein a new class is derived from an existing class.
• All Kotlin Classes have a common Superclass 'Any', it is the Default Superclass with no Super Type declared.

  class Student  // implicitly inherits from Any
  

• 'Any' Class has three methods
  1. equals()
  2. hashCode()
  3. toString()
  These methods available for all Kotlin class implicitly.
• By Default All class is Final in Kotlin, They can't be inherited.
• Use 'open' keyword, to make class inheritable,

  open class <class name>  // make class inheritable
  

• To declare explicit supertype, placer base class name after colon into the class header.

  open class Base{}
  class Derived : Base{}
  

Program for Inheritance in Kotlin

package com.includehelp

//Declare class, use 'open' keyword 
//to make class inheritable
//Class without declare primary constructor
open class Company{
    //member function
    fun getCompany(){
        println("Base Methods : Company Info")
    }
}
//Declare class using inheritance
class Department : Company() {
    //member function
    fun getDept(){
        println("Derived Method :  Dept Info")
    }
}

//Declare class, use 'open' keyword 
//to make class inheritable
open class Shape(val a:Int){
    fun getBaseValue(){
        println("Base value : $a")
    }
}
//if derived class has primary constructor 
//then base class can initialized there
//using primary constructor parameters
class Circle(val b:Int): Shape(b) {
    fun getChildValue(){
        println("Child value : $b")
    }
}


//Main Function, Entry point of program
fun main(args:Array<String>){

    //create derived class object
    val company = Department()
    //access base class function
    company.getCompany()
    //access derived class function
    company.getDept()


    //create derived class object and passed parameter
    val shape = Circle(20)
    //access base class function
    shape.getBaseValue()
    //access derived class function
    shape.getChildValue()
}

Output:

Base Methods : Company Info
Derived Method :  Dept Info
Base value : 20
Child value : 20