Implementing Empty Versions of Interface Methods with Return Types

Question

Subject probably is probably a bit long but I was stumped for a brief way to summarize my question. Let's say I have the interface below:
public interface DAO {
    ...snip...
    public Object get(int id);
    public Object[] get(String clause);
    ...snip...
}From this I want to make two concrete classes, say ClassOne and ClassTwo. Given the type of data each one is fetching, ClassOne only needs (and should only) implement get(int id) and ClassTwo only needs (and should only) implement get(String clause). This is because the first class will always deal with only one record from table_a and the second class will always deal with one or more records from table_b. So my question is what is the correct way to provide empty implementations for the unnecessary methods?
I've thought of using an adapter to implement empty methods but a) I'm not sure that makes sense and b) I still end up have to return something. Another option was maybe having multiple interfaces, one returning a single object and the other returning an array. Neither of those options felt right and looked a bit goofy when I prototyped them out. It seems to me that I wouldn't want the classes using the concrete DAO classes to be able to call the wrong method, but I don't know how to hide the unused method. Right now I just return an empty Object or Object[] for the unused method but that seems goofy too, and makes the class using ClassOne or ClassTwo know the innards of the implementations.
Anyway, any tips appreciated.
Thanks,
Pablo

Answer 1

It sounds as if the methods weren't meant to be together, and so I'm wondering if you aren't better off with two distinct interfaces, one for each method. Otherwise one solution would be to implement a method that throws an exception if it is not meant to be called.
edit: D'oh! Just when you least expect them, Ninjas! They're everywhere!
Edited by: Encephalopathic on Apr 30, 2009 1:41 PM