Symmetrical Mapping Data Structure

Question

I'm using a TreeMap to store sorted information. Both the keys and the objects indexed by them are of type String . But, what I really want is a mapping that's "symmetrical". By this I mean I can get() either object (ie String ) from the map by using the other one as a key. I'd still like it to be sorted by one of the objects. Does such a mapping structure exist? FWIW, there are no duplicate pairs in the data.

Answer 1

You can create a symmetrical mapping by adding the keys to the TreeMap symmetrically:

map.put(a, b);
map.put(b, a);

This isn't exactly a special data structure, but it sounds like it would meet your requirements.