What s the difference between `find ` and `firstOrNull ` on kotlinlang #announcements

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Title

d

dave08

02/04/2019, 11:39 AM

What's the difference between

find { }

and

firstOrNull { }

on

Iterable<T>

in the stdlib?

g

gsala

02/04/2019, 11:46 AM

There isn't a difference (https://youtrack.jetbrains.com/issue/KT-5185)

a

Anton Lakotka [JB]

02/04/2019, 11:46 AM

From source code:

/**
 * Returns the first element matching the given [predicate], or `null` if no such element was found.
 */
@kotlin.internal.InlineOnly
public inline fun <T> Iterable<T>.find(predicate: (T) -> Boolean): T? {
    return firstOrNull(predicate)
}

hence find is just an alias

d

dave08

02/04/2019, 11:49 AM

Interesting discussion over there... so most people would use

find

?

a

Anton Lakotka [JB]

02/04/2019, 11:53 AM

it depends. find is shorter, but in some cases firstOrNull may be more "expressive" in terms of readability.

for example from code context you are dealing with list of unique elements then it makes sense to use find. in case of list which may have duplicates firstOrNull now makes more sense.

d

dave08

02/04/2019, 12:14 PM

That's why I was expecting

Set<T>.find

... I was surprised it was on

Iterable

. Thanks for the confirmation 🙂!

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