Refactoring your Application to Data-Oriented Programming

Data-Oriented Programming is a programming model paradigm, alternative to Object Oriented Programming, that allows you to organize your application code differently. Its goal is the same as Object Oriented Programming: enabling the extension of a given object model by adding new types and new behavior. Since Java is an Object Oriented language, it uses tools already there such as records, sealed types (mostly interfaces), exhaustive switch expressions, and pattern matching.
This hands-on lab gives you a simple application as a starting point and uses a step by step approach to guide you through a Data-Oriented Programming refactoring. Once this refactoring is done, it shows you how to add new types and behavior so you can compare with the Object Oriented approach. By the end of this workshop, you'll have a better understanding of Data-Oriented Programming and how and where you can apply its principles in your application.

Transcript

1. Refactoring to Data Oriented Programming José Paumard Java Developer Relation Java Platform Group, Oracle Billy Korando Java Developer Advocate Java Platform Group, Oracle
2. https://dev.java @billykorando.bsky.social billy.korando@oracle.com
3. https://dev.java @josepaumard.bsky.social
4. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 4 https://dev.java/
5. Tune in! 5 Copyright © 2026, Oracle and/or its affiliates Inside Java Newscast JEP Café Road To 25 series Inside.java Inside Java Podcast Sip of Java Cracking the Java coding interview
7. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 7 Structure of the Lab
8. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 8 Is it new? The Expression Problem: how to extend statically typed data abstractions, in representations and behavior, without having to recompile the existing code. User-defined Types and Procedural Data Structures as complementary approaches to Data Abstraction." Reynolds, John C. (1975). . New Directions in Algorithmic Languages (PDF). IFIP Working Group 2.1 on Algol. pp. 157–168. Foundations of Object-Oriented Languages (FOOL), Cook, William (1990), REX School/Workshop. Lecture Notes in Computer Science. Vol. 489. Noordwijkerhout. Data Oriented Programming
9. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 9 Polymorphism - Add new subtypes - No new operations Wadler’s Answer Pattern Matching - Add new operations - No new subtypes You cannot get both  If you are not the owner of the code: Phil Wadler
10. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 10 Because it has to do with long term maintenance of your applications When your business requirements evolve: 1) How can you add behavior to your Object Model? 2) Can you remove the behavior that becomes obsolete? Why is This Problem Interesting?
11. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 11 Structure of the Lab: Step 0 3 types of relationship: 1) Push 2) Pull 3) Pubsub A_Database B_Price-monitoring C_GUI D_Fligt-BP
12. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 12 Structure of the Lab: Step 1 3 types of relationship: 1) Push 2) Pull 3) Pubsub A_Database B_Price-monitoring C_GUI D_Fligt-BP
13. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 13 Fixing the Application / DB Relation DB FlightEntity (Hibernate) Business Module
14. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 14 Fixing the Application / DB Relation DB FlightEntity (Hibernate) Business Module Application of the Dependency Inversion Principle (SOLID)
15. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 15 Fixing the Application / DB Relation DB FlightEntity (Hibernate) Business Module <I> <DTO>
16. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 16 Refactoring to Data Oriented Programming - About creating sealed types, carrying only state Record FTW! - And adding behavior outside of these types Pattern Matching FTW! Structure of the Lab: Step 2
17. 3/17/2026 Copyright © 2026, Oracle and/or its affiliates 17 Final test: adding a new type, how does it go? Initial situation: you support simple flights Extension: you need to support multileg flights Structure of the Lab: Step 3