📦 MarketApp – A Second-Hand Marketplace Welcome to MarketApp, a Java-based GUI application that allows users to buy and sell second-hand products with ease! This project demonstrates object-oriented design, Java Swing GUI, and robust feature implementation, and aligns perfectly with the project rubric requirements.

🚀 Features ✅ Core Feature Implementation

User Registration and Login

Product Listing and Filtering (by price, type, and seller)

Cart Management (add, remove, checkout)

Product Details and Negotiation Simulation

Reviews (for the app and individual sellers)

✅ Error Handling and Robustness

Graceful error handling using JOptionPane pop-ups for invalid inputs, empty fields, and incorrect data formats.

Try-catch blocks around critical sections like price parsing and negotiation.

✅ Integration of Components

Smooth integration of registration, login, product browsing, buying, and cart management using a CardLayout for seamless navigation between screens.

Shared data structures (e.g., availableProducts, cartItems, currentUser) facilitate data flow between components.

✅ Event Handling and Processing

Action listeners for buttons and combo boxes ensure responsive and interactive user experience.

List selection events trigger product details display.

✅ Data Validation

Validations for price fields (numeric only) and non-empty inputs.

Basic filtering logic for product type matching (case-insensitive).

Prevents users from buying their own products.

✅ Code Quality and Innovative Features

Modular design with clear separation of GUI components and logic.

Innovative negotiation simulation for price offers.

Custom cell renderer enhances product list readability.