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Thinking Like an Object-Oriented Designer and Programmer

When designing software, imagine building real-world things as software objects. Each object represents a thing in the system with its own information and actions.

To practice this way of thinking, focus on these questions when given a system:

  • What are the main things (entities) involved?
  • What details (attributes) does each thing have?
  • What actions (behaviors) can each thing perform?
  • How do these things connect or relate to each other?
  • Are there any important details that should be kept private or protected?

1. Introduction to OOP

Scenario 1: Library Management System

Library Management System

Imagine you are designing software to help a library keep track of its books and users.

Consider these questions:

  • What are the main things in the library system? Think about both physical things and people.
  • For each main thing, what details are important to store?
  • What actions will each thing need to perform? For example, what can happen to a book?
  • How do the things interact or work together? Which things rely on or connect with others?
  • Which details should be kept private or secure? Why might that be necessary?

Scenario 2: University Management System

Library Management System

Now think about software for managing courses, students, and staff at a university.

Ask yourself:

  • What are the key things in a university system?
  • What important details would each thing need to keep track of?
  • What kinds of actions or tasks must those things be able to do?
  • How would these things be connected or related to one another?
  • Are there details that need to be kept confidential? Who should have access to them?

This way of breaking down problems helps you see the system as a group of interacting parts, each with its own role. Taking these steps before writing any code sets a strong foundation for building clear and flexible software.

Hands-On Coding

Let's get practical. Create a class named Book that models a real book with the following features:

  1. Properties (Variables)

    • Title (text)
    • Author (text)
    • ISBN number (text or number)
    • Number of copies available (whole number)

  2. Constructor

    • Create a way to set all these properties when a new Book object is created.

  3. Getters and Setters

    • Provide methods or functions to safely get (read) and set (modify) each property
    • Make sure the number of copies cannot be set to a negative number.

  4. Methods (Behaviors)

    • A method to borrow a book: this should reduce the number of available copies by one, but only if there is at least one copy available.
    • A method to return a book: this should increase the number of available copies by one.

2. Fundamentals of Classes and Objects

Project Goal

The goal of this project is to practice Object-Oriented Programming fundamentals by developing a simple University Management System. Each group will design and implement one class independently. After all groups complete their classes, we will integrate them in a main program to demonstrate how individual components can work together to form a complete software system.

General Requirements for All Classes

Each class must include:

  • Private variables as specified in your class requirements
  • Two constructors: a default constructor and a parameterized constructor
  • Getter and setter methods for all private variables
  • toString() method that returns a formatted string representation of the object
  • Additional methods as specified for your class

Class 1: Student

Private Variables

  • studentID (String or int) - Unique identifier for the student
  • name (String) - Full name of the student
  • GPA (double) - Grade Point Average (0.0 to 4.0)
  • enrollmentYear (int) - Year the student enrolled at the university

Constructors

  1. Default constructor: Initialize all variables with default values (empty strings, 0, etc.)
  2. Parameterized constructor: Accept and initialize studentID, name, GPA, and enrollmentYear

Required Methods

  • Getter methods only for studentID and enrollmentYear (these cannot be changed after creation)
  • Getter and setter methods for name
  • Getter method only for GPA (no setter - use updateGPA method instead)
  • updateGPA(double newGPA): Update the student's GPA with validation (must be between 0.0 and 4.0)
  • toString(): Return a formatted string containing all student information
  • calculateAcademicStanding(): Return a String indicating academic standing based on GPA:
    • "Good Standing" if GPA >= 2.0
    • "Academic Probation" if GPA >= 1.5 and GPA < 2.0
    • "Academic Warning" if GPA < 1.5

Class 2: Professor

Private Variables

  • employeeID (String or int) - Unique identifier for the professor
  • name (String) - Full name of the professor
  • specialization (String) - Subject area of expertise (e.g., "Computer Science", "Mathematics")
  • yearsOfExperience (int) - Total years of teaching experience

Constructors

  1. Default constructor: Initialize all variables with default values
  2. Parameterized constructor: Accept and initialize employeeID, name, specialization, and yearsOfExperience

Required Methods

  • Getter and setter methods for all four variables
  • toString(): Return a formatted string containing all professor information
  • isExperienced(): Return true if yearsOfExperience is greater than 5, false otherwise
  • getAcademicTitle(): Return a String with academic title based on experience (e.g., "Assistant Professor" for 0-5 years, "Associate Professor" for 6-10 years, "Professor" for 11+ years)

Class 3: Course

Private Variables

  • courseCode (String) - Unique course identifier (e.g., "CS101", "MATH201")
  • courseName (String) - Full name of the course
  • credits (int) - Number of credit hours (typically 1-6)
  • semester (String) - When the course is offered (e.g., "Fall 2025", "Spring 2026")

Constructors

  1. Default constructor: Initialize all variables with default values
  2. Parameterized constructor: Accept and initialize courseCode, courseName, credits, and semester

Required Methods

  • Getter and setter methods for all four variables
  • toString(): Return a formatted string containing all course information
  • displayCourseInfo(): Print complete course details in a readable format
  • isFullCourse(): Return true if credits >= 3, false otherwise
  • getFullCourseName(): Return a String combining courseCode and courseName (e.g., "CS101: Introduction to Programming")

Class 4: Classroom

Private Variables

  • roomNumber (String) - Room identifier (e.g., "101", "A205")
  • buildingName (String) - Name or code of the building
  • capacity (int) - Maximum number of students the room can hold
  • hasProjector (boolean) - Whether the room has a projector

Constructors

  1. Default constructor: Initialize all variables with default values
  2. Parameterized constructor: Accept and initialize roomNumber, buildingName, capacity, and hasProjector

Required Methods

  • Getter and setter methods for all four variables
  • toString(): Return a formatted string containing all classroom information
  • displayClassroomInfo(): Print complete classroom details in a readable format
  • isLargeRoom(): Return true if capacity > 50, false otherwise
  • canAccommodate(int numberOfStudents): Accept a number of students and return true if the classroom capacity can accommodate them, false otherwise
  • getFullLocation(): Return a String combining building name and room number (e.g., "Building A, Room 205")

Class 5: Department

Private Variables

  • departmentName (String) - Name of the department (e.g., "Computer Science", "Mathematics")
  • location (String) - Building or floor where department offices are located
  • numberOfFaculty (int) - Total number of faculty members in the department
  • departmentHead (String) - Name of the department chairperson

Constructors

  1. Default constructor: Initialize all variables with default values
  2. Parameterized constructor: Accept and initialize departmentName, location, numberOfFaculty, and departmentHead

Required Methods

  • Getter and setter methods for all four variables
  • toString(): Return a formatted string containing all department information
  • displayDepartmentInfo(): Print complete department details in a readable format
  • addFaculty(): Increment the numberOfFaculty by 1
  • removeFaculty(): Decrement the numberOfFaculty by 1 (ensure it doesn't go below 0)
  • isLargeDepartment(): Return true if numberOfFaculty > 20, false otherwise

Submission Guidelines

  • Each group must submit a single .java file containing their class
  • Include proper comments documenting your class, variables, and methods
  • Test your class by creating objects and calling all methods to ensure they work correctly
  • Your class name must match exactly as specified above (Student, Professor, Course, Classroom, or Department)

Integration

Once all groups have completed their classes, we will create a main program that:

  • Creates objects from each class
  • Demonstrates interactions between objects (e.g., a Professor teaching a Course in a Classroom)
  • Shows how independent components combine to form a functional system