Java11 Coding Conventions Training

Key things the skill must make very clear (these are the conventions models don't follow without explicit instruction):

• Use final var for locals when the type is obvious from the RHS — never bare var
• Use List.of/Map.of/Set.of for small immutable collections, and List.copyOf etc. for defensive copies (replaces the Java 8 unmodifiableList(new ArrayList<>(...)) pattern)
• Use Collectors.toUnmodifiableList() — Stream.toList() is Java 16 and must not appear
• Prefer Optional.isEmpty(), Optional.or, ifPresentOrElse, Optional.stream(), Stream.ofNullable
• Use Predicate.not(String::isBlank) style negation
• Use String.isBlank/strip/lines/repeat instead of trim().isEmpty() and similar workarounds
• Use Files.readString / Files.writeString with the default UTF-8
• Use java.net.http.HttpClient for HTTP calls
• No records, sealed, pattern matching, text blocks, switch expressions with ->, or Stream.toList()

Step 2: Validate with test cases

After regenerating, validate the skill using the test cases in evals/evals.json.

For each test case, spawn a subagent that:

1. Reads the general skill from plugins/conventions/skills/java-coding-conventions/SKILL.md
2. Reads the generated Java 11 skill from plugins/conventions/skills/java11-coding-conventions/SKILL.md
3. Reads any input files specified in the test case
4. Completes the task described in the prompt, following both skills' conventions
5. Writes output Java files to a workspace directory

Then run the shared grading script against the outputs:

cd plugins/training
python -m shared.grade <workspace-dir>

The script checks Java 11-specific assertions:

• no-post-java11-features — no records/sealed/pattern matching/text blocks/switch expressions/Stream.toList()
• unmodifiable-collections-java11 — List.of/copyOf or Collections.unmodifiable*
• streams-over-loops, optional-for-find
• all-vars-final-or-var — allows final var alongside final

Plus general assertions (immutable fields, small methods, etc.) to verify the general skill inclusion works correctly.

Expected results

All assertions should pass for all test cases. If any fail, the conventions in the skill need strengthening in that area.

Test cases

The test cases in evals/evals.json cover:

1. Refactor OrderService — mutable state, loops, checked exceptions, null returns, long methods
2. Refactor UserProfile — mutable JavaBean with getters/setters, imperative collection code
3. Greenfield InventoryService — write a new service class from scratch

Input files for refactoring tests are in evals/files/.

Conventions reference

The authoritative conventions are in references/conventions.md. Always read that file when regenerating — it is the single source of truth for what Java 11-specific rules to include.