Contact & Group Management System

A Java Swing application for managing contacts and groups with support for phone numbers, persistent storage, and real‑time updates via the Observer pattern.

📖 Description

This system provides a user‑friendly interface to manage a personal or professional contact directory. It allows users to:

• Create, view, update, and delete contacts, each with one or more phone numbers.
• Organise contacts into groups.
• Add, update, or remove contacts within a group.
• Search and sort contacts and groups.
• Persist all data in binary files using Java serialization.

The application implements the Observer pattern to automatically refresh views when data changes (e.g., when a contact is updated, all open views reflect the change immediately).

✨ Features

👤 Contact Management

• Add, edit, and delete contacts (first name, last name, city).
• Each contact can have multiple phone numbers (region code + number).
• View detailed contact information including all phone numbers.
• Sort contacts by first name, last name, or city.
• Real‑time search filtering as you type.

📂 Group Management

• Create, edit, and delete groups with a name and description.
• Add existing contacts to a group, update contact details inside a group, or remove contacts from a group.
• View group details with a list of all members.

🔍 Search & Sort

• Live search on contacts (by name or city) and groups (by name or description).
• Sorting of contacts by any field with a single click.

💾 Data Persistence

• All data stored in three binary files:
  • Contacts.dat – all contacts
  • Groups.dat – all groups
  • GroupsContacts.dat – relationships (optional, but group contacts are serialized within groups)
• Uses Java ObjectInputStream/ObjectOutputStream for robust serialization.

🔔 Observer Pattern

• Custom MyObservable and MyObserver implementations ensure that changes made in one view (e.g., updating a contact) are automatically reflected in all other open windows (e.g., group member lists, contact lists).

🛠️ Technologies Used

• Java 8+ – Core language
• Swing – Graphical user interface
• Serialization – Data persistence
• Observer Pattern – Custom implementation for reactive UI updates
• UUID – Unique identifiers for contacts and groups

🚀 Getting Started

Prerequisites

• Java Development Kit (JDK) 8 or higher
• Any Java IDE (Eclipse, IntelliJ IDEA, NetBeans) or command‑line build tool

Running the Application

1. Clone the repository

   git clone https://github.com/yourusername/contact-manager.git
   cd contact-manager

2. Compile and run
   From your IDE, open the src/views/MainView.java class and run it.

   Or from the command line:

   javac -d bin src/**/*.java
   java -cp bin views.MainView

3. First run
   The application will create empty data files on the first launch. Start by adding a few contacts and groups to explore the features.

Building a JAR (optional)

jar cf contactmanager.jar -C bin .
java -jar contactmanager.jar

📖 Usage

Main Menu

• Click Contacts to open the contact management window.
• Click Groups to open the group management window.

Contacts View

• Add New Contact – fill in the form.
• Update Contact – select a contact and modify its fields.
• Delete Contact – confirm deletion.
• View Contact – open a detailed dialog to manage phone numbers (add, update, remove).
• Sort – use the buttons to sort by first name, last name, or city.
• Search – type in the search box to filter contacts live.

Groups View

• Add New Group – provide a name and description.
• Update Group – change the group's name or description.
• Delete Group – remove the group (contacts are not deleted).
• View Group – open a dialog to add, update, or remove contacts from the group.
• Search – filter groups by name or description.

📁 Project Structure

NFA035-main/
├── src/
│   ├── Models/                     – Domain entities
│   │   ├── Contact.java            – Contact with phone numbers
│   │   ├── Group.java              – Group with contacts
│   │   └── PhoneNumber.java        – Phone number (region + number)
│   ├── Observables/                – Custom observable base
│   │   └── MyObservable.java       – Observable implementation
│   ├── Observers/                  – Observer interface
│   │   └── MyObserver.java         – Observer callback
│   └── views/                      – GUI windows
│       ├── MainView.java           – Entry point with two buttons
│       ├── ContactsView.java       – Contact list management
│       ├── ContactUpdateView.java  – Edit contact form
│       ├── NewContactView.java     – New contact form
│       ├── GroupsView.java         – Group list management
│       ├── GroupUpdateView.java    – Edit group form
│       └── NewGroupView.java       – New group form
├── bin/                            – Compiled classes
├── Contacts.dat                    – Serialized contacts
├── Groups.dat                      – Serialized groups
├── GroupsContacts.dat              – Serialized group‑contact links (not used directly)
└── README.md

🤝 Contributing

Contributions are welcome! Feel free to open issues or submit pull requests with improvements, bug fixes, or new features.

📄 License

This project is for educational purposes. You may use and modify it under the terms of the MIT License.