Questions

1. What is:

• Class
• Object
• Method
• Constructor
• Method Overloading
• Method Overriding
• Constructor Overloading
• Encapsulation
• Inheritance
• Polymorphism

2. Analyze the Scenarios Below

k. Vehicle Maintenance Tracker (Java Program)

Design a Java program with the following requirements:

• Create a base class Vehicle with encapsulated attributes:

  • modelName
  • manufactureYear
  • private vehicleId These must be initialized using a constructor and include appropriate getter and setter for vehicleId.

• Create a subclass Car that:

  • Extends Vehicle
  • Adds attribute totalDistance (double), initialized to 0 in the constructor
  • Implements:
    • addDistance(double km)
    • showStatus() — shows model, age category (old/new), total distance
    • scheduleMaintenance() — prints maintenance message based on distance

• Demonstrate polymorphism by creating:

  • A class MaintenanceService with method performService(Vehicle v)
  • Another class overriding this to handle Car-specific servicing

• In main():

  • Create a Car object
  • Log two distance updates using addDistance()
  • Display status
  • Perform maintenance

l. Online Course Enrollment System (Java Program)

• Create a base class Person with:

  • name
  • email
  • private userId (with encapsulated getter & setter)

• Create subclass Student that:

  • Inherits Person
  • Adds completedCourses = 0
  • Implements:
    • completeCourse()
    • displayStudentInfo() — name, learning level (Beginner / Intermediate / Advanced), total courses completed
    • resetProgress()

• Add polymorphism:

  • Base class: Course with method getCourseType()
  • Subclasses: ProgrammingCourse, MathCourse (override method)

• In main():

  • Create a Student
  • Complete two courses
  • Display updated info
  • Show course type using polymorphism

m. Smart Pet Monitoring System (Java Program)

Design a Java program with the following requirements:

• Create a base class Pet with encapsulated attributes:

  • petName
  • species
  • private petId These must be initialized using a constructor and include appropriate getter and setter for petId.

• Create a subclass Dog that:

  • Extends Pet
  • Adds attribute totalActivities (int), initialized to 0 in the constructor
  • Implements:
    • logActivity(int count)
    • showDogProfile() — shows dog's name, species category (small/medium/large), activity count
    • resetActivities()

• Demonstrate polymorphism by creating:

  • A base class Activity with method activityType()
  • Subclasses WalkingActivity, FeedingActivity that override activityType()

• In main():

  • Create a Dog object
  • Record two activities using logActivity()
  • Display profile
  • Reset activity count
  • Show polymorphism using activityType()

n. Student Attendance Tracker (Java Program)

Design a Java program with the following requirements:

• Create a base class Person with encapsulated attributes:

  • name (String)
  • yearOfAdmission (int)
  • private personId (String) These must be initialized using a constructor and include appropriate getter and setter for personId.

• Create a subclass Student that:

  • Extends Person
  • Adds attributes totalClasses and attendedClasses (int), both initialized to 0 in the constructor
  • Implements:
    • addClass(int n) — increases totalClasses by n
    • attendClass(int n) — increases attendedClasses by n (but never beyond totalClasses)
    • getAttendancePercentage() — returns attendance percentage as double
    • showStatus() — prints student's name, admission category ("Senior" if yearOfAdmission <= 2022, otherwise "Junior"), attendance percentage, and eligibility ("Eligible for exam" if >= 75%, otherwise "Not eligible")

• Demonstrate polymorphism by creating:

  • A class ReportService with method generateReport(Person p) that prints a general message
  • A subclass StudentReportService that extends ReportService and overrides generateReport() to downcast and print detailed attendance report if p is a Student, otherwise print a generic message

• In main():

  • Create a Student object
  • Use addClass() and attendClass() at least twice to update totals
  • Call showStatus()
  • Create a StudentReportService object and call generateReport() with the student object to demonstrate polymorphism

o. Library Book Borrowing System (Java Program)

Design a Java program with the following requirements:

• Create a base class LibraryItem with encapsulated attributes:

  • title (String)
  • publishYear (int)
  • private itemId (String) These must be initialized using a constructor and include appropriate getter and setter for itemId.

• Create a subclass Book that:

  • Extends LibraryItem
  • Adds attributes borrowCount (int, initialized to 0) and isAvailable (boolean, initially true)
  • Implements:
    • borrow() — if isAvailable is true, increment borrowCount, set isAvailable to false, and print "Book borrowed successfully"; otherwise print "Book is currently unavailable"
    • returnBook() — sets isAvailable to true and prints "Book returned"
    • showStatus() — prints title, age category ("Classic" if publishYear < 2000, otherwise "Modern"), total borrowCount, and availability ("Available" / "Not Available")
    • needsReplacement() — prints "Replacement suggested" if borrowCount >= 50, otherwise "No replacement needed yet"

• Demonstrate polymorphism by creating:

  • A class LibraryService with method processItem(LibraryItem item) that prints a general message
  • A subclass BookService that extends LibraryService and overrides processItem() to call showStatus() and needsReplacement() if item is a Book, otherwise print a generic message

• In main():

  • Create a Book object
  • Call borrow(), returnBook(), and borrow() again to change state
  • Call showStatus() and needsReplacement()
  • Create a BookService object and call processItem() with the Book object to demonstrate polymorphism

p. Fitness Center Membership Tracker (Java Program)

Design a Java program with the following requirements:

• Create a base class Member with encapsulated attributes:

  • memberName (String)
  • joinYear (int)
  • private memberId (String) These must be initialized using a constructor and include appropriate getter and setter for memberId.

• Create a subclass GymMember that:

  • Extends Member
  • Adds attributes totalWorkoutHours (double, initialized to 0.0) and membershipType (String, e.g., "Regular" or "Premium")
  • Implements:
    • addWorkout(double hours) — increases totalWorkoutHours by hours (ignore invalid negatives)
    • showStatus() — prints member name, membership duration category ("Long-term" if (currentYear - joinYear) >= 2, else "New"; assume currentYear is 2025), membership type, and total workout hours
    • suggestPlan() — prints "Excellent engagement" if totalWorkoutHours >= 200, "Good, keep going" if between 100 and 199, "Need more regular workouts" otherwise

• Demonstrate polymorphism by creating:

  • A class MembershipService with method handleMember(Member m) that prints "Handling generic member..."
  • A subclass GymMembershipService that extends MembershipService and overrides handleMember() to downcast and call showStatus() and suggestPlan() if m is a GymMember, otherwise print a simple message

• In main():

  • Create a GymMember object with some initial data
  • Call addWorkout() at least twice with different hour values
  • Call showStatus() and suggestPlan()
  • Create a GymMembershipService object and call handleMember() with the GymMember object to demonstrate polymorphism

q. Online Course Progress Tracker (Java Program)

Design a Java program with the following requirements:

• Create a base class Course with encapsulated attributes:

  • courseName (String)
  • totalModules (int)
  • private courseCode (String) These must be initialized using a constructor and include appropriate getter and setter for courseCode.

• Create a subclass ProgrammingCourse that:

  • Extends Course
  • Adds attributes completedModules (int, initialized to 0) and difficultyLevel (String, e.g., "Beginner", "Intermediate", "Advanced")
  • Implements:
    • completeModule(int n) — increases completedModules by n, but never lets it exceed totalModules
    • getCompletionPercentage() — returns completion percentage as double
    • showStatus() — prints course name, difficulty level, completion percentage, and learning status ("On track" if percentage >= 60, "Needs attention" otherwise)
    • suggestRevision() — prints "Revise previous modules" if completion percentage is between 40 and 70, "Focus on practice problems" if > 70, "Start with basics again" if < 40

• Demonstrate polymorphism by creating:

  • A class CourseService with method reviewCourse(Course c) that prints "Reviewing generic course..."
  • A subclass ProgrammingCourseService that extends CourseService and overrides reviewCourse() to downcast and call showStatus() and suggestRevision() if c is a ProgrammingCourse, otherwise print a generic message

• In main():

  • Create a ProgrammingCourse object
  • Call completeModule() multiple times to simulate progress
  • Call showStatus() and suggestRevision()
  • Create a ProgrammingCourseService object and call reviewCourse() with the course object to demonstrate polymorphism

3. Solve the following problems using Java

(Use Class, Object, Constructor, Method, Single-Level Inheritance, Multi-Level Inheritance where appropriate.)

a. Program to check leap year b. Program to find largest among three numbers c. Program to print Fibonacci series up to N d. Program to calculate area of a circle e. Program to print all primes up to N

4. Identify the Errors and Show Output

public class Book {
    String tittle;
    string author;
    int pages;

    Book(String t, String a, int p {
        title = t;
        author = author;
        pages = pg;
    }

    void displayDetails() {
        System.out.println("Title: " + Title);
        System.out.println("Author: " + author)
        System.out.println("Pages: " + pages);
    }

    public boolean isBigBook() {
        if (pages > "300") {
            return "True";
        }
        return false;
    }
}

5. Comparison questions

1. Class vs Objects
2. Encapsulation vs Abstraction
3. Method overloading vs overriding
4. Inheritance vs Composition
5. Compile-time vs Run-time Polymorphism

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