CODEWITHSUNDEEP
scalascala-collections
Notso Penguin
Notso Penguin

Reputation: 33

The difference between Lists and Sets

What are the main differences in using an Array/list or a set. What would be a reason to use one over the other? I have looked at the documentation and it seems that they both have many common methods.

I all ready know that Lists are immutable and how sets are both immutable and mutable.

val Stuff = Array(1,2,3,4)
val Apple =  Set(1,2,3,4)

Stuff.map(x => x*2)
Apple.map(x => x*2)

Upvotes: 3

Views: 6213

Answers (2)

goral
goral

Reputation: 1265

The main difference in terms of functionality is the fact that Sets cannot contain duplicate elements.

Adding to collection where the element already exists yields no effect.

Upvotes: 4

dhg
dhg

Reputation: 52681

A Set is unordered and can't have duplicate items.

scala> Set(1,2,3,1,2,3) == Set(3,2,1)
res2: Boolean = true

Sequences (Array, List, Vector, etc) are ordered and can have repeated elements.

To use your example (which, incidentally, doesn't compile...):

val stuff = Array(1, 2, 3, 4)
val apple = Set(1, 2, 3, 4)

stuff.map(x => x % 3)  // Array(1, 2, 0, 1)
apple.map(x => x % 3)  // Set(1, 2, 0)

Upvotes: 12

Related Questions