Multi-valued hashtable in Java

Question

Is it possible to have multiple values for the same key in a hash table? If not, can you suggest any such class or interface which could be used?

Answer 1

None of the answers indicated what I would do first off.

The biggest jump I ever made in my OO abilities was when I decided to ALWAYS make another class when it seemed like it might be even slightly useful--and this is one of the things I've learned from following that pattern.

Nearly all the time, I find there is a relationship between the objects I'm trying to place into a hash table. More often than not, there is room for a class--even a method or two.

In fact, I often find that I don't even want a HashMap type structure--a simple HashSet does fine.

The item you are storing as the primary key can become the identity of a new object--so you might create equals and hash methods that reference only that one object (eclipse can make your equals and hash methods for you easily). that way the new object will save, sort & retrieve exactly as your original one did, then use properties to store the rest of the items.

Most of the time when I do that, I find there are a few methods that go there as well and before I know it I have a full-fledged object that should have been there all along but I never recognized, and a bunch of garbage factors out of my code.

In order to make it more of a "Baby step", I often create the new class contained in my original class--sometimes I even contain the class within a method if it makes sense to scope it that way--then I move it around as it becomes more clear that it should be a first-class class.