当class1对象通过反射在另一个class2中私有声明时，如何访问class1的私有变量的值？

Question

I am trying to access private field of department after passing course as an object to function. Department is a private variable in course. The solution needs to be generic as this is a reflection exercise. At run time the store object function doesn't know which type of object is being passed so i cant use type casting either. this is department class:

public class Department{
  private String departmentName;
  private Teacher departmentHOD;
}

this is Course class:

public class Course {
  private String courseNumber;
  private String semesterName;
  private String courseName;
  private Department offeringDepartment;
  private Teacher[] courseInstructors;
  private int sectionNumbers;
}

in main I pass course in a function void storeObject(Object o):

void storeObject(Object o)
{
 //in this function i need to extract all possible primitive datatype objects and save them in a data base
Class classForStorage = o.getClass();
Field[] publicFields = classForStorage.getDeclaredFields();//.getFields()
    for (int i = 0; i < publicFields.length; i++) 
    {   //  making private ones accessible
        publicFields[i].setAccessible(true);
        //Getting name and type of all attributes in the class one by one
        String fieldName = publicFields[i].getName();
        Class typeClass = publicFields[i].getType();
        String fieldType = typeClass.getName();
       ......//after this i access values by datatype and store in sql
       //but it only works for primitive data types
    }

I cant access departname using something like:

  publicFields[i].getType().getDeclaredFields()[0].setAccessible(true);
  value =(String)publicFields[i].getType().getDeclaredFields()[0].get(obj); 

this gives me illegal access exception

On a side note how can get values from the courseInstructor array.

Answer 1

Edit: "via reflection" was added to the question header after this answer was posted. If the solution must be using reflection, this answer is not applicable.

The generic solution you seek is :

 public class Course {
   private String courseNumber;
   private String semesterName;
   private String courseName;
   private Department offeringDepartment;
   private Teacher[] courseInstructors;
   private int sectionNumbers;

   //add a getter to Course 
   public Department getDepartment() {
     return offeringDepartment
   }
}

To retrieve department use

Course course = new Course();
Department department = course.getDepartment();

If 'o' object is an instance of 'Course' you can:

//cast object to Course and use getter 
((Course)o).getDepartment();

Answer 2

You're overthinking this.

void printObject( Object o ) {
    for ( Field fld : o.getClass().getDeclaredFields() ) {
        fld.setAccessible( true );
        System.out.println( fld.get( o ) );
    }
}

If you need your method to behave differently if the field is an array, use isArray .

void printObject( Object o ) {
    for ( Field fld : o.getClass().getDeclaredFields() ) {
        fld.setAccessible( true );
        Object oFldVal = fld.get( o );
        if ( fld.getType().isArray() ) {
            int iLen = Arrays.getLength( oFldVal );
            for ( int i = 0; i < iLen; ++i ) {
                printObject( Arrays.get( oFldVal, i ) );
            }
        } else {
            System.println( oFldVal );
        }
    }
}