Sorted and sortedBy in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

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What does the sorted() function do in Kotlin?

It returns a new list with the elements sorted in natural ascending order without changing the original list.

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How does sortedBy differ from sorted()?

sortedBy sorts elements based on a selector function you provide, allowing custom sorting criteria.

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Example: What is the result of listOf(3, 1, 2).sorted()?

The result is [1, 2, 3], a new list sorted in ascending order.

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Example: How to sort a list of strings by their length using sortedBy?

Use list.sortedBy { it.length } to get a list sorted by string length.

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Does sorted() or sortedBy modify the original list?

No, both return a new sorted list and leave the original list unchanged.

What does sorted() return when called on a list?

A A new list sorted in ascending order

B The original list sorted in place

C A list sorted in descending order

D An error if the list is empty

sorted() returns a new list sorted in ascending order without changing the original.

Which function lets you sort a list by a custom property?

A sorted()

B sort()

C filter()

D sortedBy()

sortedBy() sorts elements using a selector function you provide.

What will listOf("apple", "kiwi", "banana").sortedBy { it.length } return?

A ["banana", "apple", "kiwi"]

B ["apple", "kiwi", "banana"]

C ["kiwi", "apple", "banana"]

D ["kiwi", "banana", "apple"]

The list is sorted by string length: "kiwi" (4), "apple" (5), "banana" (6).

Does sorted() change the original list?

A Yes, it sorts the original list

B No, it returns a new sorted list

C Only if the list is mutable

D Only if you assign it back

sorted() always returns a new sorted list and does not modify the original.

Which of these is true about sortedBy?

A It sorts elements by a key you specify

B It only works on numbers

C It sorts elements randomly

D It sorts elements by their natural order

sortedBy sorts elements based on a key selector function you provide.

Explain how sorted() and sortedBy() work in Kotlin and when you would use each.

Think about sorting numbers vs sorting by a property like length or age.

Describe a real-life example where sortedBy is more useful than sorted().

Imagine sorting a list of fruits by how long their names are.