LinkedHashMap: iterate forwards or backwards from a specific entry?

[michaelhkay]

I can see how to iterate all the entries in a LinkedHashMap, in order.

But if I select a specific entry, using get(key), how do I iterate forwards or backwards from that point, without scanning the whole map?

The name, "LinkedHashMap" suggests that it ought to be possible...

[pivovarit]

This is not possible at the moment, but this is a great feature idea!

[pivovarit]

I'm afraid I need to move the target from 0.11 to 1.0 - at the moment, it's not really possible to achieve with desired performance characteristics (we can't O(1) lookup element's position). We'll be revisiting the internals of all collections, and then we'll circle back again here

[michaelhkay]

Thanks for the feedback. For info, we've moved off VAVR for the moment in favour of a home-grown structure which works well for most of our use cases but has some bad "worst-case" effects so it's not necessarily a final solution.

If you're interested in knowing what we're up to, here's a recent blog posting.

https://blog.saxonica.com/mike/2025/08/implementing-jnodes.html