"Song Hongkang Learning Diary 18" interface

One interface
The 1 interface can be seen as an abstract class, a function that consists of a constant (public static final decoration) and an abstract method (public abstract decoration)
Interface aa{
(public static final) int age;
(public abstract) void method ();
}
2 Interfaces and interfaces: Inheritance relationships, multiple inheritance. Interface AA extends bb,cc{}
Classes and interfaces: Implementing relationships, multiple implementations. Class AA implements bb,cc,dd{}
Classes and classes: inheritance, multiple inheritance. Class AA extends bb{}
3 interfaces without constructors;
Class 4 implements an interface to be instantiated by overriding the interface's abstract method;
Otherwise, it is still an abstract class.

The design pattern of the factory method of two interfaces: The design interface class defines an abstract method, which is given to the subclass implementation.
Three-agent mode: When the proxy class executes, it is actually being executed by the proxy class. Obj=new Objectimp () before;(as an instance of the proxy class, which is the proxy class)

"Song Hongkang Learning Diary 18" interface