Kotlin program | Extension function features

Kotlin | Extension function features: Here, we are implementing a Kotlin program to demonstrate the example of Extension function features.
Submitted by IncludeHelp, on May 31, 2020

Extension function

  • Kotlin provides the ability to add more functionality to the existing class without inheriting them.
  • This is done via a special declaration called "Extension'.
  • When a function added into an existing User-defined or Library class called 'Extension Function'.
  • It can also define extensions of functions and properties for companion objects.

Program for extension function features in Kotlin

package com.includehelp

// Declare class
class MyClass1{
    // Member function
    fun sayHello(){
        println("Say Hello")

// Declare class
class MyClass2{
    // create companion object to call method with class name
    companion object{
        // companion object function
        fun display(){
            println("Display from Companion Object !!")

// define Extension function for MyClass1
fun MyClass1.greetExtn(){
    println("Greetings from Extension Function !!")

// define extension for Int Class
fun Int.isOdd(){
        println("Number is ODD")

// Define Extension function for MyClass2 Companion object
fun MyClass2.Companion.printData(){
    println("Extension function for Companion object !!")

// Main Function, Entry point of Program
fun main(){
    // Create Instance
    val myClass1 = MyClass1()

    // Called member function of class

    // Called extension function

    // Called Int Class extension Function

    // Called companion object member function

    // Called companion object extension function


Say Hello
Greetings from Extension Function !!
Number is ODD
Display from Companion Object !!
Extension function for Companion object !!

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