Delegation based Kotlin interview questions and answers

What is Kotlin delegation?

Kotlin supports the “delegation” design pattern by introducing a new keyword “by”. Using the keyword or delegation methodology. Kotlin allows the derived class to access all of the implemented public methods of an interface through a specific object.

Example

1. Live Demo
2. interface Base {
3. fun printMe() //abstract method
4. }
5. class BaseImpl(val x: Int) : Base {
6. override fun printMe() { println(x) } //implementation of the method
7. }
8. class Derived(b: Base) : Base by b // delegating the public method on the object b
10. fun main(args: Array<String>) {
11. val b = BaseImpl(10)
12. Derived(b).printMe() // prints 10 :: accessing the printMe() method
13. }

Output
10