What is the difference between abstract classes and interfaces?

In terms of design , Abstraction is the abstraction of a class , Is a template design , Interface is the abstraction of behavior , It's a code of conduct .

• Java Provides and supports the creation of abstract classes and interfaces . They have something in common , The difference is ： All methods in the interface are implicit and abstract , Abstract classes can contain both abstract and non abstract methods .

• Classes can implement many interfaces , But you can only inherit from one abstract class . Class does not implement all methods declared by abstract classes and interfaces , Of course , under these circumstances , Class must also be declared abstract .

• Abstract classes can implement an interface without providing an interface method implementation .

• Java The variables declared in the interface are all final Of . Abstract classes can contain non final The variable of .

• Java The member functions in the interface are... By default public Of . The permission modifier of an abstract class member function can be private,protected Or is it public .

• The interface is absolutely Abstract , Cannot be instantiated . Abstract classes cannot be instantiated either , however , If it contains #main(String[] args) Method can be called .