Collection size and emptiness checks in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What Kotlin function checks if a collection has no elements?

The isEmpty() function returns true if the collection contains no elements.

beginner

How do you check if a Kotlin collection has at least one element?

Use the isNotEmpty() function, which returns true if the collection contains one or more elements.

beginner

What property gives the number of elements in a Kotlin collection?

The size property returns the count of elements in the collection.

intermediate

Why is it better to use isEmpty() instead of size == 0 in Kotlin?

Using isEmpty() is clearer and can be more efficient because it may avoid counting all elements if the collection supports fast emptiness checks.

beginner

What will listOf(1, 2, 3).isNotEmpty() return?

It returns true because the list contains three elements.

Which Kotlin function checks if a collection is empty?

A isEmpty()

B isNotEmpty()

C hasElements()

D count()

The isEmpty() function returns true if the collection has no elements.

What does collection.size return in Kotlin?

A The last element of the collection

B The number of elements in the collection

C The first element of the collection

D True if collection is empty

size gives the count of elements in the collection.

Which function returns true if a Kotlin collection has one or more elements?

A isEmpty()

B hasElements()

C isNotEmpty()

D count()

isNotEmpty() returns true if the collection is not empty.

Why might isEmpty() be preferred over size == 0?

A It can be more efficient and clearer

B It is less readable

C It always returns false

D It counts elements twice

isEmpty() can be more efficient and expresses intent clearly.

What is the result of emptyList<Int>().isNotEmpty()?

A Throws an error

B true

C null

D false

An empty list returns false for isNotEmpty().

Explain how to check if a Kotlin collection is empty or not.

Think about functions that return true or false based on collection content.

Describe why using isEmpty() might be better than checking size == 0 in Kotlin collections.

Consider both code clarity and how the collection might be implemented.