How to access a value of a private variable of a class1 when the class1 object is privately declared in another class2?

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. 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.