Since one of the newer versions of
Java (I think since Java 5) you cannot import classes or interfaces from the default package anymore.
In older versions of Java, it was possible to do that, like this:
import SomeInterface; But that feature has been removed - you'll get an error message if you try to do this in Java 5 or 6. You must put your interface in a package other than the default pacakge if you want to be able to use it in a different package.