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Kotlin Inheritance


Kotlin Inheritance (Subclass and Superclass)

In Kotlin, it is possible to inherit class properties and functions from one class to another. We group the "inheritance concept" into two categories:

  • subclass (child) - the class that inherits from another class
  • superclass (parent) - the class being inherited from

In the example below, MyChildClass (subclass) inherits the properties from the MyParentClass class (superclass):

Example

// Superclass
open class MyParentClass {
  val x = 5
}

// Subclass
class MyChildClass: MyParentClass() {
  fun myFunction() {
    println(x) // x is now inherited from the superclass
  }
}

// Create an object of MyChildClass and call myFunction
fun main() {
  val myObj = MyChildClass()
  myObj.myFunction()
}
Try it Yourself »

Example Explained

Use the open keyword in front of the superclass/parent, to make this the class other classes should inherit properties and functions from.

To inherit from a class, specify the name of the subclass, followed by a colon :, and then the name of the superclass.

Why And When To Use "Inheritance"?

- It is useful for code reusability: reuse properties and functions of an existing class when you create a new class.