# Java Best Practices

## Project Structure
project-root/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/company/project/
│   │   │       ├── api/          # API interfaces
│   │   │       ├── config/       # Configuration
│   │   │       ├── controller/   # Request handlers
│   │   │       ├── model/        # Domain model
│   │   │       ├── repository/   # Data access
│   │   │       ├── service/      # Business logic
│   │   │       └── util/         # Utilities
│   │   └── resources/
│   │       ├── config/          # Configuration files
│   │       ├── db/             # Database scripts
│   │       └── static/         # Static resources
│   └── test/
│       ├── java/              # Test classes
│       └── resources/         # Test resources
├── docs/                      # Documentation
├── .gitignore
├── README.md
└── pom.xml                    # or build.gradle

## Architecture
- Follow microservices principles if building distributed systems
- Use layered architecture (Controller → Service → Repository)
- Keep services small and focused
- Design for failure
- Make services independently deployable

## Dependencies
- Keep dependencies up to date
- Use dependency version management
- Minimize external dependencies
- Use appropriate dependency scopes
- Include only what you need

## Security
- Never store secrets in code
- Use HTTPS everywhere
- Implement proper authentication/authorization
- Validate all inputs
- Keep security dependencies updated
- Follow the principle of least privilege

## Database
- Use connection pooling
- Implement proper transaction management
- Use database migrations
- Don't trust user input in queries
- Keep database credentials secure

## Testing
- Write unit tests for business logic
- Include integration tests
- Use proper test data
- Mock external dependencies
- Test error scenarios

## Monitoring
- Implement health checks
- Add proper logging
- Include metrics collection
- Monitor performance
- Set up alerts for critical issues

## Documentation
- Document public APIs
- Keep documentation up to date
- Include setup instructions
- Document configuration options
- Maintain changelog

## Performance
- Use caching where appropriate
- Implement pagination for large datasets
- Profile your application
- Optimize database queries
- Use async operations when beneficial

## Error Handling
- Implement global error handling
- Use appropriate exception types
- Log errors properly
- Return proper error responses
- Include error tracking
