Use Case of Lazy Initialization

Loading Optional Features in a Web Application

Scenario

In a Spring Boot e-commerce application, there is an email notification service that sends order confirmation emails. However, this service is optional—it should only be initialized when email notifications are enabled.

Problem without Lazy Initialization

If the email notification service is eagerly initialized, it loads on every application startup, even when the feature is disabled. This increases startup time and unnecessarily loads dependencies like SMTP configurations.

Solution with Lazy Initialization

Mark the email service as lazy, ensuring it is only loaded when actually needed (i.e., when an order is placed and email notifications are enabled).

Implementation

@Component
@Lazy
public class EmailNotificationService {
    
    public EmailNotificationService() {
        System.out.println("EmailNotificationService Initialized");
    }

    public void sendOrderConfirmation(String email, String orderId) {
        System.out.println("Sending order confirmation to: " + email);
    }
}

Usage in Order Processing

@Service
public class OrderService {
    
    private final EmailNotificationService emailService;

    public OrderService(EmailNotificationService emailService) {
        this.emailService = emailService;
    }

    public void processOrder(String email, String orderId, boolean emailEnabled) {
        System.out.println("Processing Order: " + orderId);
        if (emailEnabled) {
            emailService.sendOrderConfirmation(email, orderId);
        }
    }
}

Behavior

• If emailEnabled = false, the EmailNotificationService never initializes, saving memory and startup time.

• If emailEnabled = true, the service initializes on demand and sends the email.

Benefits of Lazy Initialization in this Case

• Faster Application Startup – The email service isn’t loaded unless required.

• Efficient Resource Utilization – Avoids loading email configurations & SMTP dependencies when not needed.

• Better Scalability – Reduces overhead in applications where certain features are optional.