Performance wise, what would be better? A list with function to fetch for a certain ID ```val listOf...

# announcements

[Sebastien Leclerc Lavallee]

Performance wise, what would be better?
A list with function to fetch for a certain ID

val listOfItems: List<Item> = listOf<Item>
fun getItemWithId(id: String): Item {
  return listOfItems.filter { it.id == id }.first()
}

A map of Item per String

val mapOfItems: Map<String,Item>

Or any other solution I didn’t think of?
Thanks 🙂

[mathew murphy]

Map should be faster unless the list is very small. If the list is really big you might want to look at something like a trie.

[marstran]

You can use the find function, instead of doing filter + first.

[marstran]

Now, whether you want to want to create a map or use find everytime depends on how many times you need to use it. Creating a map has a performance cost up front, but when you have the map it's fast. Using find will make you loop through the list every time.

[Thomas]

return listOfItems.first { <http://it.id|it.id> == id }

[Sebastien Leclerc Lavallee]

Thanks for the answers!

[Thomas]

@Sebastien Leclerc Lavallee you already have the answer, but more generally if you aren't familiar with "big O" notation https://developerlife.com/2018/08/16/algorithms-in-kotlin-1/ looks to be a good introduction. Knowing the space/time complexity of algorithms will help you answer questions like this in the future.