Expense Tracker Application

A backend REST API application built with Java Spring Boot for expense tracking, featuring expense management, categorization, and comprehensive statistics endpoints.

Features

• RESTful API with full CRUD operations
• SQLite database for data persistence
• Expense and Category management
• Comprehensive statistics endpoints:
  • Total expenses
  • Average expense
  • Daily statistics
  • Monthly statistics
  • Category-based statistics

Technology Stack

• Java 21
• Spring Boot 3.5.7
• Spring Data JPA
• SQLite Database
• Maven

Project Structure

expense-tracker/
└── backend/
    └── expense-tracker/
        ├── src/
        │   └── main/
        │       ├── java/com/example/expense_tracker/
        │       │   ├── model/           # Entity classes
        │       │   ├── repository/      # Data access layer
        │       │   ├── service/         # Business logic
        │       │   └── controller/      # REST endpoints
        │       └── resources/
        │           └── application.properties
        └── pom.xml

Setup and Installation

Prerequisites

• Java 21 or higher
• Maven

Backend Setup

1. Navigate to the backend directory:

cd backend/expense-tracker

2. Build the project:

./mvnw clean install

3. Run the Spring Boot application:

./mvnw spring-boot:run

The backend server will start on http://localhost:8080

API Endpoints

Categories

• GET /api/categories - Get all categories
• GET /api/categories/{id} - Get category by ID
• POST /api/categories - Create new category
• PUT /api/categories/{id} - Update category
• DELETE /api/categories/{id} - Delete category

Expenses

• GET /api/expenses - Get all expenses
• GET /api/expenses/{id} - Get expense by ID
• POST /api/expenses - Create new expense
• PUT /api/expenses/{id} - Update expense
• DELETE /api/expenses/{id} - Delete expense
• GET /api/expenses/category/{categoryId} - Get expenses by category

Statistics

• GET /api/expenses/statistics - Get overall statistics (total, average)
• GET /api/expenses/statistics/daily - Get today's statistics
• GET /api/expenses/statistics/monthly - Get current month's statistics
• GET /api/expenses/statistics/by-category - Get expenses grouped by category

Usage

Use the REST API endpoints to:

1. Create Categories: Create expense categories (e.g., Food, Transport, Entertainment)
2. Add Expenses: Add expenses with description, amount, and category
3. Filter Expenses: Query expenses by specific categories
4. View Statistics: Get statistics on your spending including total, average, daily, and monthly summaries
5. Manage Data: Update or delete expenses and categories as needed

Database

The application uses SQLite database which is automatically created as expense_tracker.db in the backend project root directory when you first run the application.

Features in Detail

Expense Management

• CRUD operations for expenses (description, amount, category)
• Retrieve all expenses with timestamps
• Filter expenses by category
• Get individual expense by ID

Category Management

• CRUD operations for categories (name, description)
• Retrieve all categories
• Unique category names enforced
• Cascade deletion (deleting a category removes associated expenses)

Statistics

• Overall statistics (total expenses, average expense)
• Daily expense tracking
• Monthly expense tracking
• Category-based expense grouping

Development

The backend uses Spring Boot with JPA/Hibernate for database operations. SQLite dialect is configured for compatibility.