what is the advantage of interface over abstract classes?

Question

In Java, abstract classes give the ability to define both concrete and abstract methods whereas interfaces only give the ability to implement abstract methods. I believe overrid

Answer 1

In OOP (mostly independent of a concrete language) abstract classes are a re-use mechanism for the class hierarchy for behaviour and structure which isn't complete on its own. Interfaces are mechanism for specification of requirements on a module (e.g. class) independently of the concrete implementation. All other differences are technical details, important is different usage.