Java interface knowledge point

Java interface knowledge point

1. The class can implement multiple interfaces;

2. The basic unit of object-oriented programming is type );

3. The interface is a design expression;

4. The interface is not implemented;

5. You cannot create an interface instance;

 

6. How to declare the interface:

 

Public interface comparable {

}

7. How to declare the interface:

Use the keyword interface;

8. Which three types of members can be declared through the interface;

A. constant;

B. method;

C. Nested classes and interfaces;

9. constants declared in the interface are implicitly public, static, and final;

10. Static methods cannot be abstracted;

 

11. methods defined in interfaces are implicitly defined as abstract;

12. interfaces can inherit multiple interfaces;

13. The interface defines a type through abstract conventions;

14. A class can only inherit one other class;

15. The interface provides a method of multi-inheritance;

16. abstract classes provide partial or full implementations;

17. Any Main class to be inherited, whether abstract or not, should be the implementation of an interface;

18. mark an interface as an interface that does not declare any methods;

19. The interface can be inherited using the keyword extends.