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Get Started Free →Use when you need to apply data-oriented programming best practices in Java — including separating code (behavior) from data structures using records, designing immutable data with pure transformation functions, keeping data flat and denormalized with ID-based references, starting with generic data structures converting to specific types when needed, ensuring data integrity through pure validation functions, and creating flexible generic data access layers. This should trigger for requests such
.claude/skills/jabrena-144-java-data-oriented-programming/SKILL.md| Test case | Without → With | Effect | Δ tokens | Δ turns |
|---|---|---|---|---|
| case-05 | ✗→✓ | ▲ Improved | 2% | 0% |
| case-04 | ✗→✓ | ▲ Improved | -24% | 0% |
| case-07 | ✗→✓ | ▲ Improved | -27% | 0% |
| case-20 | ✗→✓ | ▲ Improved | -1% | 0% |
| case-11 | ✓→✗ | ▼ Worse | -17% | 0% |
Apply data-oriented programming in Java: separate data from behavior with records, use immutable data structures, pure functions for transformations, flat denormalized structures with ID references, generic-to-specific type conversion when needed, pure validation functions, and flexible generic data access layers. All transformations should be explicit, traceable, and composed of clear pure functional steps.
What is covered in this Skill?
Scope: The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.
Before applying any data-oriented programming recommendations, ensure the project compiles. Compilation failure is a blocking condition. After applying improvements, run full verification.
./mvnw compile or mvn compile before applying any change./mvnw clean verify or mvn clean verify after applying improvementsRun ./mvnw compile or mvn compile and stop immediately if compilation fails.
Read references/144-java-data-oriented-programming.md and identify candidates for data/behavior separation and immutable transformations.
Implement selected improvements using records, pure transformation functions, flat structures, and explicit validation.
Run ./mvnw clean verify or mvn clean verify after applying improvements.
For detailed guidance, examples, and constraints, see references/144-java-data-oriented-programming.md.
| Case | Status | Duration (ms) | Turns | Tokens | Tool calls | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Without | With | Δ | Without | With | Δ | Without | With | Δ | Without | With | Δ | ||
case-05 | fail→pass | 16,389 | 11,367 | -31% | 1 | 1 | 0% | 2,498 | 2,548 | +2% | 0 | 0 | — |
case-06 | pass→pass | 15,046 | 8,640 | -43% | 1 | 1 | 0% | 2,400 | 1,964 | -18% | 0 | 0 | — |
case-01 | fail→fail | 17,698 | 4,592 | -74% | 1 | 1 | 0% | 3,044 | 900 | -70% | 0 | 0 | — |
case-02 | fail→fail | 3,201 | 5,507 | +72% | 1 | 1 | 0% | 327 | 891 | +172% | 0 | 0 | — |
case-03 | pass→pass | 16,015 | 13,244 | -17% | 1 | 1 | 0% | 2,285 | 2,651 | +16% | 0 | 0 | — |
case-04 | fail→pass | 16,184 | 7,306 | -55% | 1 | 1 | 0% | 2,542 | 1,925 | -24% | 0 | 0 | — |
case-07 | fail→pass | 11,574 | 3,777 | -67% | 1 | 1 | 0% | 1,540 | 1,120 | -27% | 0 | 0 | — |
case-08 | pass→pass | 9,620 | 2,355 | -76% | 1 | 1 | 0% | 1,379 | 960 | -30% | 0 | 0 | — |
case-09 | pass→pass | 16,086 | 13,302 | -17% | 1 | 1 | 0% | 2,593 | 2,769 | +7% | 0 | 0 | — |
case-10 | pass→pass | 15,353 | 8,853 | -42% | 1 | 1 | 0% | 2,492 | 2,011 | -19% | 0 | 0 | — |
case-11 | pass→fail | 22,611 | 17,532 | -22% | 1 | 1 | 0% | 4,124 | 3,430 | -17% | 0 | 0 | — |
case-12 | pass→fail | 15,712 | 20,884 | +33% | 1 | 1 | 0% | 2,861 | 4,037 | +41% | 0 | 0 | — |
case-13 | pass→pass | 22,758 | 16,069 | -29% | 1 | 1 | 0% | 3,849 | 3,377 | -12% | 0 | 0 | — |
case-14 | pass→pass | 17,864 | 16,178 | -9% | 1 | 1 | 0% | 2,926 | 3,494 | +19% | 0 | 0 | — |
case-15 | pass→pass | 9,331 | 5,737 | -39% | 1 | 1 | 0% | 1,408 | 1,477 | +5% | 0 | 0 | — |
case-16 | pass→pass | 17,917 | 15,579 | -13% | 1 | 1 | 0% | 3,407 | 3,421 | +0% | 0 | 0 | — |
case-17 | pass→pass | 13,984 | 10,860 | -22% | 1 | 1 | 0% | 2,176 | 2,330 | +7% | 0 | 0 | — |
case-18 | pass→pass | 10,207 | 5,770 | -43% | 1 | 1 | 0% | 1,664 | 1,461 | -12% | 0 | 0 | — |
case-19 | pass→pass | 15,053 | 12,529 | -17% | 1 | 1 | 0% | 2,374 | 2,518 | +6% | 0 | 0 | — |
case-20 | fail→pass | 13,437 | 9,463 | -30% | 1 | 1 | 0% | 2,213 | 2,198 | -1% | 0 | 0 | — |
case-21 | pass→pass | 20,569 | 12,771 | -38% | 1 | 1 | 0% | 3,426 | 2,948 | -14% | 0 | 0 | — |
case-22 | pass→pass | 17,474 | 7,110 | -59% | 1 | 1 | 0% | 3,024 | 1,763 | -42% | 0 | 0 | — |
DecimalAI ran this skill against gemini-3.6-flash twice over the same eval suite — once with the skill loaded and once without — and compared the two runs case by case. 22 cases were attempted, and 20 counted toward the lift figure. The other 2 produced results that are not comparable between the two arms, so they are excluded from the headline rather than averaged into it. The headline lift of +9 percentage points is the difference between those two pass rates over the 20 comparable cases. 3 cases got worse with the skill loaded, and they are included in that figure.
Without the skill loaded, the model failed this case. With it loaded, the same prompt on the same model passed. This is one improved case from the latest verified run; every case, including any that regressed, is in the table above.
Other measured skills in the registry, with their headline benchmark lift.