Java object-oriented attention point 2

Four types of permission modifiers:

　　　　

Common modifiers used by the class and its composition:

* A: modifier:
* Permission modifier: private, default, Protected,public
* Status modifier: static,final
* Abstract modifier: Abstraction
* B: Class:
* Permission modifier: default modifier, public
* Status modifier: Final
* Abstract modifier: Abstraction

* The most used is: public

* C: Member Variable:
* Permission modifier: private, default, Protected,public
* Status modifier: static,final

* The most used is: private

* D: Construction Method:
* Permission modifier: private, default, Protected,public

* The most used is: public

* E: Member Method:
* Permission modifier: private, default, Protected,public
* Status modifier: static,final
* Abstract modifier: Abstraction

* The most used is: public

* F: In addition to the combination of rules:
* Member variable: public static final
* Member Method:
* public static
* Public abstract
* Public Final

Internal class overview and Access features:

Internal class Access features
* A: The inner class can access the members of the external class directly, including the private.
* B: External class to access members of an inner class, you must create an object.

Static member Inner class:　

The members inner class is accessed statically after being modified by:
* External class name. Internal class Name Object name = new External class name. Internal class name ();

Local internal classes access local variables:

　　　　Local internal class access local variables must be final decorated

The format and understanding of anonymous inner classes:

* A: Anonymous inner class
* is a simplified notation of the inner class.
* B: Premise: There is a class or interface
* The class can be either a concrete class or an abstract class.
* C: Format:
*
New class name or interface name () {
Override method;
}
* D: What is the essence?
* is an anonymous object that inherits the class or implements the interface's subclass.

Java object-oriented attention point 2