Kotlin Kotlin OOP 2

Question 1

What is an object declaration in Kotlin?

Accepted Answer

A singleton instance created using the `object` keyword

Answer

An `object` declaration in Kotlin creates a singleton — a class with exactly one instance, initialized lazily on first access.

Question 2

How do you implement an interface in Kotlin?

Accepted Answer

Using a colon followed by the interface name

Answer

Kotlin uses a colon (`:`) for both class inheritance and interface implementation, followed by the interface or superclass name.

Question 3

What does the `override` keyword do in Kotlin?

Accepted Answer

Explicitly marks a method as overriding a parent class or interface member

Answer

The `override` modifier is required in Kotlin to explicitly indicate that a method overrides a member from a parent class or interface.

Question 4

What is a primary constructor in Kotlin?

Accepted Answer

A constructor declared in the class header

Answer

The primary constructor is declared directly in the class header after the class name and can include property declarations.

Question 5

What is the purpose of `init` block in a Kotlin class?

Accepted Answer

To run initialization code when an instance is created

Answer

The `init` block contains initialization code that runs immediately after the primary constructor when a class instance is created.

Kotlin Practice Test