Kotlin Kotlin Type System and Null Safety 2

Question 1

Which keyword is used to check if an object is of a specific type in Kotlin?

Accepted Answer

is

Answer

instanceof

Answer

typeof

Answer

checkType

Question 2

What does the unsafe cast operator `as` do when the object is not of the target type?

Accepted Answer

Throws ClassCastException

Answer

Returns null

Answer

Returns the original object

Answer

Compiles but produces undefined behavior

Question 3

What does the safe cast operator `as?` return when the cast is unsuccessful?

Accepted Answer

null

Answer

ClassCastException

Answer

The original object

Answer

An empty instance

Question 4

What keyword defines a type alias in Kotlin?

Accepted Answer

typealias

Answer

alias

Answer

typedef

Answer

typeref

Question 5

What is the `Nothing` type in Kotlin primarily used for?

Accepted Answer

Functions that always throw or loop infinitely

Answer

Representing void functions

Answer

Storing null values

Answer

Generic type wildcards

Question 6

After `if (x is String)`, how does Kotlin handle the variable `x` inside the block?

Accepted Answer

x is auto-cast to String via smart casting

Answer

x must be explicitly cast with `(x as String)`

Answer

x remains the original nullable type

Answer

x is widened to Any

Question 7

What is `Any` in Kotlin's type system?

Accepted Answer

The root supertype of all non-nullable Kotlin types

Answer

A nullable supertype equivalent to Java's Object

Answer

The supertype of all nullable Kotlin types

Answer

A dynamic type bypassing compile-time checks