Val for immutable references in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does val mean in Kotlin?

val declares a read-only (immutable) reference. Once assigned, you cannot change what it points to.

beginner

Can you reassign a new value to a val variable in Kotlin?

No, you cannot reassign a new value to a val variable. It is immutable after initialization.

beginner

How is val different from var in Kotlin?

val is immutable (cannot be reassigned), while var is mutable (can be reassigned).

beginner

Example: What happens if you try to reassign a val variable?<br>

val x = 10
x = 20

This will cause a compile-time error because x is declared with val and cannot be reassigned.

intermediate

Does val guarantee the object it points to is immutable?

<p>No, <code>val</code> only means the reference cannot change. The object itself can still be mutable if its class allows it.</p>

What does val declare in Kotlin?

A A mutable reference

B A function

C An immutable reference

D A class

val declares an immutable reference that cannot be reassigned.

Can you reassign a new value to a val variable after initialization?

A No, never

B Only inside functions

C Yes, anytime

D Only if it is a number

val variables cannot be reassigned after they are initialized.

Which keyword allows reassignment in Kotlin?

A var

B val

C const

D fun

var declares a mutable variable that can be reassigned.

If you declare val list = mutableListOf(1, 2, 3), can you add elements to list?

A No, because list is immutable

B Only if you reassign list

C No, because val forbids any changes

D Yes, because the object is mutable

val means the reference cannot change, but the mutable list object can be modified.

What error occurs if you try to reassign a val variable?

A Runtime error

B Compile-time error

C No error

D Logical error

Reassigning a val causes a compile-time error in Kotlin.

Explain what val means in Kotlin and how it differs from var.

Think about whether you can change the variable after setting it.

Describe a situation where using val is better than var.

Consider when you want to protect data from accidental changes.