When the object attribute is a reference type (case) and FIG memory analysis

 

Programming is completed the following requirements:
Class Grade categories:

Properties: number, name, address,
defined: constructor with no arguments, there constructor parameter
definition method: displaying information classes.
Student categories:
attributes: Student ID, name, age, where the class
definition method: display student information (student number, name, sex, age, class number, class name )　　// g red annotation is a reference type with grade class created (28 lines of code)

Note: where the class should be the class of the class type
test class:
create a class object through the constructor have parameters,
by constructor with no arguments, students create a class object
call information display method for displaying student information

. 1  class Grade {
 2          // attributes: ID, name, address 
. 3          int NUM;
 . 4          String name;
 . 5          String address;
 . 6  
. 7          // constructor with no arguments: 
. 8          public Grade () {
 . 9          
10          }
 . 11          // has parameters configured method 
12 is          public Grade ( int NUM, String name, String address) {
 13 is              the this .num = NUM;
 14              the this .name = name;
 15              the this .Address = address;
 16          }
17          // method: display information about students 
18          public  void Show () {
 19              System.out.println ( "Class number:" + num + "\ n Class Name:" + name + "\ n class address" + address) ;
 20 is          }
 21 is  }
 22 is  class Student {
 23 is      // properties: school, name, sex, age, where the class 
24      int ID;
 25      String name;
 26 is      char sex;
 27      int Age;
 28      Grade Grade new new G = () ;     // Note: when g has no value, the default value is null
 29      // method: display student information (student number, name, sex, age, class number, class name) 
30     public  void the showInfo () {
 31 is          System.out.println ( "Student information is as follows:" );
 32          System.out.println ( "Student ID:" + id + "\ n Name:" + name + "\ n Gender: "+ sex +" \ n Age: "+ age +" \ n number of classes: "+ g.num +" \ n class name: "+ g.name);
 33 is      }
 34 is  }
 35  class the Test {
 36      public  static  void main (String [] args) {
 37 [          // by reference constructor has created an object class 
38 is          Grade Grade = new new Grade (123, "class one", "one hundred and one" );
39          // by no constructor parameters, to create an object class students 
40          Student = S new newStudent ();
 41 is          // call the display method of displaying information student information 
42 is          s.showInfo ();
 43 is      }
 44 is }