There have been a few threads about mutable numbers and I'll try to summarize the ideas.
1) What package/project should these classes go in?
2) What type of naming scheme should we use?
3) Comparision between my (matth) initial implementation vs. Geronimos
I can't find the Mutable classes in Geronimo anymore. Perhaps they were removed?
One of the primary differences I noted was that the Geromino classes contained additional methods such add add(int), subtract(int), and things like that. I find this similar to Henri's suggestion that MutableString contain StringUtils-like methods (split(), capitalize(), etc).
Another difference was the existence of a Mutable interface I (hen) think.
4) List of classes to have mutable versions of
We would need Int, Boolean and Float as well IMHO. Otherwise the get() becomes a typecast pain.