Kotlin Kotlin Classes and Object-Oriented Programming 3

Question 1

What is the `by lazy` delegation in Kotlin?

Accepted Answer

Initializes a property only on first access and caches the result

Answer

Creates a mutable property initialized on every access

Answer

Delegates a property to a companion object

Answer

Marks a property as optional

Question 2

How do you define a property with a custom getter in Kotlin?

Accepted Answer

Defining a `get()` function inside the property declaration

Answer

Using @Getter annotation

Answer

Using `getProperty()` method

Answer

Properties cannot have custom getters

Question 3

What is the difference between `abstract class` and `interface` in Kotlin?

Accepted Answer

Abstract classes can have constructors and state; interfaces cannot have constructors or mutable state

Answer

Interfaces support state; abstract classes do not

Answer

There is no difference

Answer

Interfaces can only have abstract methods

Question 4

What does the `inner` keyword enable in Kotlin?

Accepted Answer

Allows the nested class to access members of the outer class

Answer

Prevents the nested class from being accessed outside the file

Answer

Creates a static nested class

Answer

Marks the class as internal visibility

Question 5

What is an enum class in Kotlin?

Accepted Answer

A class representing a fixed set of named constants

Answer

A class that can only hold numeric values

Answer

A class with exactly one instance

Answer

A class that maps keys to values

Question 6

How does Kotlin's `copy()` function work in data classes?

Accepted Answer

It creates a new instance with optionally modified properties

Answer

It creates a deep copy of all nested objects

Answer

It serializes the object to JSON

Answer

It clones the object's memory address