Kotlin Kotlin Basics and Syntax

Question 1

Which keyword is used to declare an immutable variable in Kotlin?

Accepted Answer

val

Answer

In Kotlin, `val` declares a read-only (immutable) variable, while `var` declares a mutable variable.

Question 2

What is the correct way to define a nullable String in Kotlin?

Accepted Answer

String?

Answer

In Kotlin, appending `?` to a type makes it nullable, so `String?` can hold a String value or null.

Question 3

Which of the following is NOT a valid Kotlin data type?

Accepted Answer

Integer

Answer

Kotlin uses `Int`, `Double`, and `Float` as built-in types; `Integer` is a Java wrapper class, not a Kotlin type.

Question 4

What does the `?.` operator in Kotlin do?

Accepted Answer

Performs a safe call on a nullable object

Answer

The safe call operator `?.` calls a method or accesses a property only if the object is non-null; otherwise it returns null.

Question 5

Which keyword is used to define a constant at the top level in Kotlin?

Accepted Answer

const val

Answer

`const val` is used to declare compile-time constants in Kotlin, which must be at the top level or inside an object.

Kotlin Practice Test