🏥 Medical Appointment Booking System

A Java-based console application that enables patients to book medical appointments, while admins manage doctors using advanced Java features like OOP, annotations, reflection, and custom exception handling — all without file handling to keep the focus on core Java principles.

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📌 Features

• 👤 User Types: Abstract User class with two main roles: Patient, Doctor, and Admin
• 🗓️ Appointment Booking: Patients can book appointments with available doctors
• ✅ Appointment Completion: Mark appointments as completed, which re-enables the doctor
• 🔐 Admin Role Security: Role-based access using custom annotations and reflection
• ⚠️ Robust Error Handling: Custom exception InvalidAppointmentException for booking/management errors
• 💡 No File Handling: Focus entirely on OOP, Java Collections, Reflection, Annotations, and Exception Handling

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🧱 Project Structure

🔷 Abstract Class: User

• Fields: id, name
• Abstract method: void showProfile()

👨‍⚕️ Class: Doctor (extends User)

• Field: boolean available = true
• Getter/setter & overrides showProfile()

🧑‍💼 Class: Patient (extends User)

• Overrides showProfile()

📅 Class: Appointment

• Fields:
  • Patient
  • Doctor
  • String status = "Scheduled"
• Constructor sets doctor as unavailable
• Method completeAppointment() sets status to "Completed" and re-enables the doctor
• Provides getStatus() and appointmentDetails()

⚠️ Custom Exception: InvalidAppointmentException

• Thrown if:
  • No doctors are available
  • Appointment index is invalid or already completed

🛡️ Custom Annotation: @Security(role = "Admin")

• Retention: RUNTIME
• Target: TYPE
• Used to secure admin-only actions via reflection

🔑 Class: Admin (extends User)

• Annotated with @Security(role = "Admin")
• Method: removeDoctor(List<Doctor> doctors, String doctorId) validated via reflection

🧠 Class: AppointmentSystem

• Fields:
  • List<Patient> patients
  • List<Doctor> doctors
  • List<Appointment> appointments
• Methods:
  • registerPatient(Patient patient)
  • registerDoctor(Doctor doctor)
  • Appointment bookAppointment(Patient patient)
  • void completeAppointment(int index)
  • void showAllDoctors()
  • void showAllAppointments()

🏁 Class: Main

• Interactive Menu:
  • 1. Register Patient
  • 2. Register Doctor
  • 3. Book Appointment
  • 4. Show All Doctors
  • 5. Show All Appointments
  • 6. Complete Appointment
  • 7. Exit