Google collections
How often have your needed lookups based on keys as well as values in a Map? Some programmers (read <1%) worth their salt look at such an opportunity to write their own collection class. However most others end up cribbing about the collections library.
Well, rescue is at hand now.
Look up google-collections.
See BiMap? Exactly what you need!
If you ever needed multiple values attached to a single key; well, here’s MultiMap.
To the credit of the library designers; they are still upholding the java.util.collections tradition of providing classes with static methods that operate on or return the new collection types. See the class names ending in collection type plurals i.e. Multimaps, Multisets etc.
