Kotlin Kotlin Type System and Null Safety 3

Question 1

What is the key difference between `Any` and `Any?` in Kotlin?

Accepted Answer

Any? is the supertype of all types including nullable, while Any excludes null

Answer

Any can hold null while Any? cannot

Answer

There is no practical difference

Answer

Any is for objects only while Any? includes primitives

Question 2

What is a 'platform type' in Kotlin?

Accepted Answer

A type from Java interop with unknown nullability, denoted as Type!

Answer

A type used only in Kotlin Multiplatform

Answer

A primitive type optimized for JVM performance

Answer

A type specific to the Android platform

Question 3

How does Kotlin differ from Java in handling numeric type conversions?

Accepted Answer

Kotlin requires explicit conversion functions like toInt() or toLong()

Answer

Kotlin automatically widens numeric types like Java

Answer

Kotlin only converts between same-size types automatically

Answer

Kotlin has no primitive numeric types at all

Question 4

What is `Unit` in Kotlin equivalent to in Java?

Accepted Answer

void

Answer

int

Answer

Object

Answer

Void (boxed)

Question 5

What is the primary benefit of sealed classes in Kotlin's type system?

Accepted Answer

They allow exhaustive when expressions without an else branch

Answer

They prevent all subclassing permanently

Answer

They make class instances non-nullable

Answer

They enable runtime type erasure

Question 6

Which scope function executes a block only when the value is non-null and passes it as `it`?

Accepted Answer

let

Answer

run

Answer

apply

Answer

with

Question 7

In Kotlin, what happens when you attempt to use an `Int?` (nullable Int) directly in arithmetic without null handling?

Accepted Answer

A compilation error occurs

Answer

Kotlin auto-unboxes it safely treating null as 0

Answer

Kotlin treats null as 0 in arithmetic

Answer

A runtime NullPointerException occurs