Abstract class and Interface

When to use abstract class, first of all, it is a class, and its openness is lower than that of the interface. The interface is just a pure "contract": it only contains the interface and its definition, and some constants. Abstract class can contain some implementation methods, that is, some public implementations. The benefit is that subclass can obtain the methods implemented by abstract, or overload it, but if the base class behavior orCodeYou need to consider its impact on the subclass. In addition, interfaces can be inherited in terms of inheritance.