kotlin 擴展類的功能

擴展功能 (Extension function)

• Kotlin provides the ability to add more functionality to the existing class without inheriting them.

  Kotlin可以在不繼承現有類的情況下為其添加更多功能。

• This is done via a special declaration called "Extension'.

  這通過稱為“擴展”的特殊聲明來完成。

• When a function added into an existing User-defined or Library class called 'Extension Function'.

  當函數添加到現有的用戶定義或庫類中時，稱為“ 擴展函數 ”。

• It can also define extensions of functions and properties for companion objects.

  它還可以定義伴隨對象的功能和屬性的擴展。

Kotlin擴展功能功能程序 (Program for extension function features in Kotlin)

package com.includehelp// Declare class class MyClass1{// Member functionfun sayHello(){println("Say Hello")} }// Declare class class MyClass2{// create companion object to call method with class namecompanion object{// companion object functionfun 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(){if(this%2==0){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 Instanceval myClass1 = MyClass1()// Called member function of classmyClass1.sayHello()// Called extension functionmyClass1.greetExtn()// Called Int Class extension Function24.isOdd()// Called companion object member functionMyClass2.display()// Called companion object extension functionMyClass2.printData() }

Output:

輸出：

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

翻譯自: https://www.includehelp.com/kotlin/extension-function-features.aspx

kotlin 擴展類的功能

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