Hi all I was wondering is there a better way to create `set` kotlinlang #getting-started

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Title

a

antoniomarin

12/02/2019, 4:30 PM

Hi all, I was wondering is there a better way to create

set

or

distinct

lists from a list of objects based on their property? Currently I’m looping through each user and adding them one by one to the

set

val userEmails = mutableSetOf<String>()
users.forEach {
    userEmails.add("Adding unique email: ${it.email}")
}
print(userEmails)

s

serebit

12/02/2019, 4:34 PM

val userEmails = users.map { it.email }.toSet()

🤔 1

👍 2

❤️ 1

a

antoniomarin

12/02/2019, 4:36 PM

I saw

distinct

as well, does anyone knows performance wise whats the difference between the two?

Thanks all

s

Shawn

12/02/2019, 4:39 PM

Actually, sorry, what I posted doesn’t exactly do what you’d want

Campbell had it right the first time, more or less

a

antoniomarin

12/02/2019, 4:40 PM

Yes but if I created regular list I could use

distinct

to add unique values 🙂

s

Shawn

12/02/2019, 4:42 PM

performance-wise they’d be more or less identical, or at least they should on the JVM after a few runs

I’d be surprised if HotSpot couldn’t figure out what you were doing here

s

serebit

12/02/2019, 4:43 PM

So to summarize, the following work:

users.map { it.email }.toSet() // returns Set

users.map { it.email }.distinct() // returns List

👍 1

thanks for making unnecessary changes to how markdown works, slack :)

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