Organizing interface, abstract, extends, and implements after returning to Java after a long time

When studying Java, these things often come up.interface abstract extends implementsEven if you have seen the names before, ...
Ars Technica

interfaces and abstract classes, what am i doing wrong?

I would like MyCorpEmployees to have MyCorpEmployee overlords and underlings, and OtherEmployees to have OtherEmployee overlords and underlings. or, i did yesterday. i'm really thinking along the ...