Unify - College Community & Marketplace App

A comprehensive Android social platform designed for college students to connect through community hubs and trade items via an integrated marketplace. Employed MVVM architecture development pattern.

Overview

Unify is a dual-purpose mobile application that combines social networking with e-commerce functionality. Students can join community hubs based on their interests, participate in threaded discussions, and buy/sell items within their campus community—all in one unified platform.

Key Features

Community Hubs

• Create and join interest-based communities
• Browse hubs by category (Academic, Social, Sports, Arts, etc.)
• Hub creators have moderation capabilities and can manage members

Threaded Discussions

• Share posts with rich text and images
• Full-featured comment system with nested replies
• Real-time updates across all users
• Save posts to "Saved Stuff" for easy access

Integrated Marketplace

• Special post type for buying/selling items with pricing and contact info
• Filter marketplace items by category (Electronics, Textbooks, Furniture, etc.)
• Shopping cart for easy item tracking
• Support for product images

User Features

• Secure Firebase authentication
• Profile management for posts, hubs, and saved content
• Recent Activity tracking showing posts you've commented on and new replies to your comments
• University affiliation display

Technical Architecture

Frontend

• Language: Kotlin
• UI Framework: Jetpack Compose (declarative UI)
• Navigation: Jetpack Navigation Component
• State Management: MutableState with remember/LaunchedEffect
• Material Design: Material3 components

Backend & Services

• Database: Cloud Firestore (NoSQL)
• Authentication: Firebase Authentication
• Storage: Firebase Storage
• Real-time Sync: Firestore real-time listeners

Data Models

• Posts: Unified model supporting both regular and market posts with isMarketPost flag
• Comments: Hierarchical structure with parentCommentId for nested replies
• Users: Profiles with authentication info and university affiliation
• Hubs: Community entities with creator info and member lists

Technical Highlights

• Complete Firebase integration with real-time listeners and CRUD operations
• Smart post system using single model for both regular and market posts
• Intelligent comment tracking that filters direct replies to user comments
• Separate storage systems for cart items and saved posts
• Base64 image encoding for inline storage and display
• Proper lifecycle management with LaunchedEffect
• Type-safe Kotlin with null safety

Setup & Installation

1. Clone the repository

2. Open in Android Studio (Hedgehog or later)

3. Add Firebase configuration:

   • Create a Firebase project at console.firebase.google.com
   • Download google-services.json
   • Place in app/ directory

4. Enable Firebase services:

   • Authentication (Email/Password)
   • Cloud Firestore
   • Firebase Storage

5. Build and run on emulator or physical device

Future Enhancements

• Direct messaging between users
• Push notifications for replies and marketplace activity
• Camera/gallery image uploads
• Advanced search with filters
• User reputation system
• In-app transactions
• Hub analytics
• Dark mode support

Technologies

• Kotlin
• Jetpack Compose
• Firebase (Firestore, Auth, Storage)
• Material Design 3
• Android SDK 34