Package structure for a Java project?

java

best-practices

package-management

maven

byAnton Shumikhin·Mar 2, 2025

Structure your Java packages by domain concepts like customer, inventory, or billing rather than by generic service, controller, or model categories. This is called package by feature, enhancing cohesion and enabling easier navigation.

Example structure:

com.company.product
├─ customer
│  ├─ CustomerService.java //Handle all your customer needs 
│  ├─ Customer.java // Every person counts!
│  └─ CustomerRepository.java // Where are all those customers hiding?
├─ inventory
│  ├─ InventoryService.java // Taking stock of things
│  ├─ Item.java // You gotta have stuff
│  └─ InventoryRepository.java // Where's all that stuff?
└─ billing
   ├─ BillingService.java // Show me the money!
   ├─ Invoice.java // Need a receipt?
   └─ BillingRepository.java // Keeping tabs

This modularizes components, facilitates teamwork, and supports agile practices.

Key principles

Follow Maven's standard structure

Maven's standard project layout is widely acknowledged for its efficiency and organization. Its familiarity across most open-source Java projects is a major advantage. Use reverse domain naming, such as com.mycompany, to instill uniqueness and enhance organization.

Adjust for Java web applications

In a Java web application, set clear guidelines on structuring the package layers for web components, services, and repositories. Consider this: placing controllers in a web or controller package within their respective domain feature can help map functionalities to specific areas.

Regular updates and evolution

Just as business requirements evolve, your codebase should too. Review and update your package structure periodically to accommodate evolving project needs. But remember, don't overcomplicate; maintain a balance between complexity and manageability.

Maven for smooth transitions

Maven's standard directory layout acts as a blueprint, a guiding principle even if Maven is not in use. Adhering to this layout makes it easier to adopt build tools and integration with other projects in the future.

Code documentation is key

Every package name should be logical, often derived from your project's design documentation. This promotes better understanding and clarity for anyone who interacts with your code.

Vital practices

Keep things intuitive

Insist on an intuitive package layout. Avoid complex structures as they can quickly turn into a maintenance nightmare.

Keep groupings logical

Group packages by project function and deployment for easier navigation and understanding. It's like stacking different types of books separately—a no-brainer,right?