Summary caused by inheritance of static internal classes by static internal classes

1. Inheritance of static classes

 Public     Static     Class  Productinfo {
  Public     Static     Final  String p_id  =     "  ID  " ;
  Public     Static     Final  String product_type  =     "  ID  "  ;
  Public     Static     Final String p_name  =     "  ID  "  ;
  Public     Static     Final  String price  =     "  ID  " ;
  Public     Static     Final  String pay_category  =     "  ID  "  ;
  Public     Static     Final String rating  =     "  ID  "  ;
  Public     Static     Final  String icon_url  =     "  ID  " ;
  Public     Static     Final  String short_description  =     "  ID  "  ;
  Public     Static    Final  String app_size  =     "  ID  "  ;
  Public     Static     Final  String source_type  =     "  ID "  ;
  Public     Static     Final  String author_name  =     "  ID  "  ;
  Public     Static    Final  String ratings_count  =     "  ID  "  ;
  Public     Static     Final  String special_flag  =     " ID  "  ;

  Public  String p_id;
  Public  String product_type;
  Public  String name;
  Public  String price;
  Public  String pay_category;
  Public  String rating;
  Public String icon_url;
  Public  String short_description;
  Public  String app_size;
  Public  String source_type;
  Public  String author_name;
  Public  String ratings_count;
  Public  String special_flag;

}

  Public    Static     Class  Productdetailinfo  Extends  Productinfo {
  Public  String packagename;
  Public  String version_code;
  Public  String comments_count;
  Public  String download_count;
  Public String long_description;
  Public  String publish_time;
  Public  String screenshot_1;
  Public  String screenshot_2;
  Public  String screenshot_3;
  Public  String screenshot_4;
  Public  String screenshot_5;
  Public String version_name;
  Public  String uses_permission;

} 

Can this be done?

Before answering this question, let's first think about how to use the static keyword?

First, when you want to make a variable irrelevant to the instance object of its class, no matter how many new objects are generated, the data is only stored in the memory.

For example, a constant, because you may reference this variable in other classes, and you do not want to create a new object, you can only use the static keyword.

Type 2: When you want a method not to be associated with the instance object of its class.

When to use internal classes

When Class A needs to use the Instance Object of class B and class B also uses the variable or method of Class A, Class B needs to be defined as the internal class of Class. If Class B is not allowed to use the variables or methods of Class A, and other external classes frequently use the variables or methods of Class B, you can set Class B to a static internal class of Class.

Analyze the precedingCode:

This static class is a static internal class of the gfanstore class.

1. Why are these two classes defined as static internal classes?

Because the static internal class does not depend on its external class, and no external class object is created in real time, we can still create internal class objects, when we want to create a productinfo Instance Object in other classes, if it is a simple internal class, then we need to first create the Instance Object of the gfanstore class (only in this way can this internal class be loaded into the memory) before creating

The instance object of productinfo. For a simple internal class, we usually only use it inside the external class. For example, in a view, I need to use the adapter, then I can use an internal class to create a sub-class of baseadapter. This adapter is not allowed in other views, so it is appropriate to use the internal class, however, if we need to use this class in other classes, we need to define it as static so that this static internal class can be used as an external class, for example, for the above two static internal classes, I need to create their instance objects in the view. I can directly create new objects, which is very simple.

2. Inheritance of static internal classes

Static internal classes inherit static internal classes, but it looks awkward.

Appendix:

Referencing a netizen'sArticleIs fully written.

Http://lavasoft.blog.51cto.com/62575/179484/

Another article is to indirectly implement multi-class inheritance through internal classes.

Http://jiangzhengjun.javaeye.com/blog/658353