I need to store data in memory where I map one or more key strings to an object, as follows:

"green", "blue" -> object1
"red", "yellow" -> object2

I need to be able to efficiently receive a list of objects, where the strings match some boolean criteria, such as:

("red" OR "green") AND NOT "blue"

I'm working in Java, so the ideal solution would be an off-the-shelf Java library. I am, however, willing to implement something from scratch if necessary.

Anyone have any ideas? I'd rather avoid the overhead of an in-memory database if possible, I'm hoping for something comparable in speed to a HashMap (or at least the same order of magnitude).