Hey :slightly_smiling_face: can I `map` a `SortedS...

# announcements

[snackycracky]

Hey 🙂 can I map a SortedSet without transitioning the whole thing to a List ?

[diesieben07]

collection.mapTo(targetCollection) { ... }

[diesieben07]

So e.g. collection.mapTo(TreeSet()) { ... }

[snackycracky]

ah thanks. I’ll check that out

[diesieben07]

Normal map would preserve it, too (by adding to a list). When using mapTo the resulting order depends on the collection you are mapping to. If you are mapping to a HashSet for example you won't get any ordering guarantees.

[diesieben07]

If you use LinkedHashSet you will get same order as source.

[diesieben07]

If you use TreeSet you will get order based on comparing entries

[snackycracky]

The definition of the map-to is: Applies the given transform function to each element of the original collection and appends the results to the given destination. so I would assume a treeset would preserve the comparator I provided…

[snackycracky]

why do you think the linkedHashSet will get the same order ? Can you explain this ?

[diesieben07]

Because LinkedHashSet preserves iteration order. mapTo will iterate through your source collection and add the mapped element to the LinkedHashSet

[diesieben07]

So the resulting set will have the same order as your source collection

[snackycracky]

ok thanks

[diesieben07]

It acts like a for loop, basically

[diesieben07]

Reading from source and appending to the target collection

[snackycracky]

yeah that’s what is sais. Make sense

[Alowaniak]

The "appending" might be a bad word choice though, it's "adding" to the destination collection, which might be appending depending on the collection