👛 Smart Wallet: Automated Expense Manager

Smart Wallet is an intelligent Android application built in Java that simplifies personal finance tracking. By leveraging Google ML Kit OCR, the app allows users to scan physical receipts, automatically extract transaction details, and visualize spending habits without manual data entry.

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✨ Key Features

• 📸 Instant Receipt Scanning: Capture receipt images using CameraX integration or select from the gallery.
• 🔍 AI Data Extraction: Automatically parses the following using Google ML Kit:
  • Merchant Name: Heuristically identified from the receipt header.
  • Total Amount: Smart detection of "Total" keywords and currency patterns.
  • Transaction Date: Regex-based matching for multiple date formats.
• 📂 Smart Categorization: Rule-based logic that automatically sorts expenses into categories (Food, Travel, Groceries, etc.).
• 📊 Spending Visualizations: Interactive Pie and Bar charts powered by MPAndroidChart for instant financial insights.
• 💾 Local-First Privacy: Built with Room (SQLite) for fast, offline-capable storage. (Note: This version avoids Firebase for enhanced user privacy and zero-config setup).

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🛠 Tech Stack

Component	Technology
Language	Java 8+
OCR Engine	Google ML Kit (Text Recognition)
Database	Room Persistence Library (SQLite)
Camera	Android CameraX API
Visuals	MPAndroidChart
Architecture	MVVM Pattern with LiveData

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🏗 Implementation Details

1. Data Layer (Room)

The app utilizes a local-first approach using the Room database to ensure speed and privacy.

• Entity: Expense.java (stores id, merchantName, amount, date, and category).
• DAO: ExpenseDao.java handles CRUD operations and aggregate queries for the dashboard charts.

2. Processing Logic (ML Kit)

• ReceiptScanner: High-level wrapper for the ML Kit TextRecognizer.
• ReceiptParser: Uses specialized Regex to extract data:
  • Date: Scans for patterns like MM/DD/YYYY, DD-MM-YYYY, or Month DD, YYYY.
  • Total: Searches for keywords (Total, Amount, Paid) followed by numeric values.
  • Merchant: Analyzes the top-most text blocks to identify the store name.
• CategoryClassifier: Assigns categories based on keyword mapping (e.g., "Shell" -> "Travel", "Walmart" -> "Groceries").

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📁 Project Structure

app/src/main/java/com/smartwallet/
├── data/
│   ├── AppDatabase.java       # Room database setup
│   ├── Expense.java           # Data Entity
│   └── ExpenseDao.java        # Database access methods
├── ml/
│   ├── ReceiptScanner.java    # ML Kit Text Recognition bridge
│   ├── ReceiptParser.java     # Logic for Date/Amount/Merchant extraction
│   └── CategoryClassifier.java # Logic for auto-categorization
├── ui/
│   ├── MainActivity.java      # Dashboard with Charts & List
│   ├── CameraActivity.java    # CameraX capture interface
│   └── ExpenseDetailActivity.java # Data review & manual correction screen
└── utils/
    └── DateUtils.java         # Formatting helpers