AAD AAD Kotlin & Programming Fundamentals

Question 1

Which Kotlin keyword is used to declare a read-only variable that cannot be reassigned after initialization?

Accepted Answer

val

Answer

The val keyword declares a read-only (immutable reference) variable in Kotlin that cannot be reassigned, similar to final in Java.

Question 2

What is a lambda expression in Kotlin?

Accepted Answer

An anonymous function that can be stored in a variable and passed as an argument

Answer

A lambda in Kotlin is an anonymous function defined with curly braces {} that can be passed as an argument or stored in a variable.

Question 3

What does the Elvis operator (?:) do in Kotlin?

Accepted Answer

Returns the left-hand expression if non-null, otherwise returns the right-hand expression

Answer

The Elvis operator ?: returns the left-hand value if it is non-null; otherwise, it returns the right-hand fallback value.

Question 4

What is a data class in Kotlin primarily used for?

Accepted Answer

Holding data with auto-generated equals(), hashCode(), toString(), and copy() methods

Answer

A Kotlin data class automatically generates equals(), hashCode(), toString(), copy(), and componentN() functions based on the constructor properties.

Question 5

What does the safe-call operator (?.) do in Kotlin?

Accepted Answer

Calls the method only if the object is non-null, otherwise returns null

Answer

The safe-call operator ?. invokes a property or method only if the receiver is non-null; if it is null, the entire expression evaluates to null.

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