Question

(Student Inberitance Hierarchy) Draw an inheritance hierarchy for students at a university similar to the hierarchy shown in Fig. 9.2. Use Student as the superclass of the hierarchy, then extend Student with classes UndergraduateStudent and GraduateStudent. Continue to extend the hierarchy as deep (i.e., as many levels) as possible. For example, Freshman, Sophomore, Junior and Senior might extend UndergraduateStudent, and Doctoral Student and MastersStudent might be subclasses of GraduateStudent. After drawing the hierarchy, discuss the relationships that exist between the classes. [Note: You do not need to write any code for this exercise.]

Short answer

The inheritance hierarchy starts with 'Student' as the superclass. 'UndergraduateStudent' and 'GraduateStudent' are subclasses of 'Student'. 'Freshman', 'Sophomore', 'Junior', and 'Senior' extend 'UndergraduateStudent', while 'DoctoralStudent' and 'MastersStudent' are subclasses of 'GraduateStudent'. Subclasses represent more specific student types and inherit attributes from their immediate superclass.

Step-by-step solution

Identify the base class

The first step in designing an inheritance hierarchy is to identify the most general class that will act as a base for other classes. In this scenario, the base class is 'Student'. This superclass will contain the attributes and methods that are common to all types of students at the university.

Determine direct subclasses

Next, we determine the subclasses that directly inherit from 'Student' superclass. In this case, there are two direct subclasses: 'UndergraduateStudent' and 'GraduateStudent'. These classes will inherit attributes and methods from 'Student' and may also have additional features specific to each type of student.

Expand the hierarchy for UndergraduateStudent

Under 'UndergraduateStudent', we can create more specific classes representing each year of study. The classes 'Freshman', 'Sophomore', 'Junior', and 'Senior' will extend the 'UndergraduateStudent' class, pertaining to the first, second, third, and fourth year of the undergraduate program, respectively.

Expand the hierarchy for GraduateStudent

For the 'GraduateStudent' branch, we have two subclasses: 'DoctoralStudent' and 'MastersStudent'. Each of these classes represents a different level of graduate study. They inherit from 'GraduateStudent', which in turn inherits from 'Student'.

Discuss the relationship between classes

In the hierarchy, 'UndergraduateStudent' and 'GraduateStudent' are both subclasses of 'Student', meaning they inherit the characteristics of a Student. 'Freshman', 'Sophomore', 'Junior', and 'Senior' are subclasses of 'UndergraduateStudent', indicating they are more specialized forms of 'UndergraduateStudent'. Similarly, 'DoctoralStudent' and 'MastersStudent' specialize 'GraduateStudent'. Each subclass can have additional attributes and methods that are specific to that level of study or type of student.

Key concepts

Student Superclass

Understanding the concept of a superclass is fundamental when learning about inheritance hierarchies. In the context of a university, the 'Student' superclass forms the foundation of our hierarchy. It encompasses the characteristics and behaviors that are common to all students, regardless of their level of study. This includes properties such as name, student ID, and enrollment status, as well as methods for registering for courses or accessing academic records.

The superclass serves to streamline code by avoiding repetition. Without a superclass, each type of student would need to have redundant code for these shared features. With the 'Student' superclass, these common traits are defined once and then inherited by all subclasses. This reduces errors and promotes code reusability, demonstrating the power of object-oriented design principles.

Inheritance allows subclasses to enhance or modify the inherited behaviors, exemplified by how 'UndergraduateStudent' and 'GraduateStudent' build upon the baseline provided by 'Student'. Through the lens of educational software, we ensure that the system recognizes all individuals as students first, then provides additional functionalities based on their specific student type.

UndergraduateStudent Class

Delving deeper into the hierarchy takes us to the 'UndergraduateStudent' class, which inherits from the 'Student' superclass. This class represents the group of students who are pursuing their bachelor's degrees. It holds attributes and methods unique to undergraduate students, like declaring a major, minor, or being part of an honors program.

Subclasses such as 'Freshman', 'Sophomore', 'Junior', and 'Senior' reflect the advancement through the four years of undergraduate studies. Each of these subclasses not only inherits features from 'UndergraduateStudent' but also customizes the educational experience to their specific year. For instance, a 'Freshman' might have orientation events, while a 'Senior' could have access to capstone project resources.

It's critical that these classes are crafted thoughtfully to provide a system that recognizes the nuanced differences between students at different stages, while also enforcing the commonalities that tie them together as undergraduates. This approach supports a personalized educational journey within a structured framework.

GraduateStudent Class

Moving up the academic ladder, the 'GraduateStudent' class is a direct descendant of the 'Student' superclass, primarily serving those enrolled in post-bachelor's degree programs. This distinct subclass could include advanced research tools, thesis submission processes, and funding or grant application methods that cater specifically to graduate-level education.

The 'GraduateStudent' class further branches out into 'DoctoralStudent' and 'MastersStudent', each with its own set of specialized attributes and methods. A 'DoctoralStudent' might have attributes relating to dissertation research and teaching assistantships, whereas a 'MastersStudent' may focus on project-based learning and professional internships. These subclasses provide a clear, tailored experience for each level of graduate study, manifesting the adaptability and depth of an inheritance hierarchy in modeling real-world entities and relationships.

Overall, the 'GraduateStudent' class exemplifies how an education system can evolve to support the advanced academic and professional development of its students, ensuring that their specific needs are addressed through a well-structured object-oriented programming framework.