In my application I have:
FileParser interface with one method:HashSet<WordDescription> readWordsList(File file);
Strust2 Action class: FileUploadAction which has fileParser property.
In general I don't need instance of FileParser - readWordsList method can be static but I can't do it in interface. I set the method abstract and injected some implementation of FileParser to FileUploadAction as singleton.
Do you think its good solution? I'm not sure and I'm looking for something better. Have you got any ideas?