A simple command-line Contact Book written in Java to showcase OOP concepts like encapsulation, abstraction, and modularity.

• ✅ Add new contacts
• ✅ View all contacts (sorted alphabetically)
• ✅ Search contact by name
• ✅ Update contact (name, phone, email)
• ✅ Delete contact by name
• ✅ Export contacts to contacts.txt
• ✅ Handles invalid user input gracefully (e.g., entering strings for menu options)

• Encapsulation – Private fields and public getters/setters in Contact.java
• Abstraction – Logical separation of responsibilities into methods
• Modularity – Clean separation of classes and methods
• Collections – Used ArrayList and Iterator for managing contacts
• Stream API – Used to perform checks like duplicate names

ContactBook/
├── src/
│ ├── Contact.java // Contact model class
│ └── ContactBook.java // Main app logic
├── contacts.txt // (Generated after exporting)