Kotlin Kotlin Extensions and Delegates

Question 1

What is an extension function in Kotlin?

Accepted Answer

A function added to an existing class without modifying its source code

Answer

A function defined inside a subclass

Answer

A function that extends the return type

Answer

An overloaded function

Question 2

Can extension functions access private members of the extended class?

Accepted Answer

No, they can only access public and internal members

Answer

Yes, always

Answer

Yes, but only within the same module

Answer

Yes, but only for data classes

Question 3

What is an extension property in Kotlin?

Accepted Answer

A property added to an existing class without modifying its source

Answer

A property that extends the type of another property

Answer

A property with a custom getter and setter

Answer

A delegated property

Question 4

What does `by lazy` do in Kotlin?

Accepted Answer

Initializes a property lazily on first access using a lambda

Answer

Creates a background thread

Answer

Marks a property as nullable

Answer

Delegates a property to another object

Question 5

Which standard delegate observable notifies you when a property value changes?

Accepted Answer

observable

Answer

lazy

Answer

vetoable

Answer

notNull

Question 6

What does `by` keyword do in Kotlin class declarations?

Accepted Answer

Delegates interface implementation to another object

Answer

Marks the class as internal

Answer

Indicates the class extends another

Answer

Creates a companion object