Mutable vs immutable interfaces in Kotlin - Quick Revision & Key Differences

Recall & Review

beginner

What is an immutable interface in Kotlin?

An immutable interface provides read-only access to data. It does not allow changes to the data it exposes.

beginner

What does a mutable interface allow you to do?

A mutable interface allows you to change or update the data it exposes, such as adding, removing, or modifying elements.

beginner

Give an example of a Kotlin immutable interface.

List<T> is an immutable interface in Kotlin. It allows reading elements but not changing the list.

beginner

Give an example of a Kotlin mutable interface.

MutableList<T> is a mutable interface in Kotlin. It allows adding, removing, and updating elements in the list.

intermediate

Why use immutable interfaces when mutable ones exist?

Immutable interfaces help prevent accidental changes, making code safer and easier to understand. They are good for sharing data without risk of modification.

Which Kotlin interface allows modifying the collection?

A MutableList

B List

C Set

D Map

MutableList allows adding, removing, and updating elements, while List is read-only.

What happens if you try to add an element to a List in Kotlin?

A List converts to MutableList automatically

B Compilation error

C Runtime exception

D Element is added successfully

List is immutable and does not have methods to add elements, so trying to add causes a compilation error.

Why prefer immutable interfaces in Kotlin?

A They use less memory

B They run faster than mutable interfaces

C They allow more methods

D They improve safety by preventing unwanted changes

Immutable interfaces prevent accidental data changes, making code safer and easier to maintain.

Which interface would you use to change elements in a Kotlin list?

A List

B Set

C MutableList

D Iterable

MutableList supports modification methods like add, remove, and set.

What is a key difference between MutableList and List in Kotlin?

A MutableList supports modification, List does not

B List supports modification, MutableList does not

C Both support modification

D Neither supports modification

MutableList allows changes; List only allows reading.

Explain the difference between mutable and immutable interfaces in Kotlin.

Think about whether you can change the data or only read it.

Why might you choose to use an immutable interface over a mutable one?

Consider safety and clarity in your code.