java-language
Modern Java 21+ language standards including Records, Pattern Matching, and Virtual Threads. Use for Java language constructs or Java-to-Java upgrades; defer Kotlin, tests, formatting/build tools, CompletableFuture, builder patterns, and isolated null-handling questions.
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Static analysis is a first line of defense, not a guarantee. Read the source
SKILL.md
Java Language Patterns
Priority: P0 (CRITICAL)
Implementation Guidelines
- Records: Use record for immutable DTOs/Value Objects. Records auto-generate equals, hashCode, toString. Avoid Lombok @Data on Pojos.
- Local Variables: Use
varfor inferred types. Explicitly type interface variables. - Switch: Use Switch Expressions (->) and Pattern Matching over complex if/else chains.
- Text Blocks: Use
"" (Text Blocks)for JSON, SQL, or multi-line strings. - Pattern Matching: Use
instanceofwith pattern binding:if (obj instanceof String s). - Sealed Classes: Use sealed interface/class with permits clause for domain-driven restricted hierarchies. Switch expressions then exhaustive switch (compiler-verified).
- Collections: Use
List.of(),Map.of(), andSet.of()for immutable collections. - Streams: Use
stream()pipelines for functional transformations. Use.toList()(Java 16+). - Optional: Utilize
Optional<T>for return types. Use.ifPresentOrElse()or.orElseThrow(). - Virtual Threads: Favor
Executors.newVirtualThreadPerTaskExecutor()for I/O-heavy workloads.
Anti-Patterns
- No Nulls: Return Optional or empty collections; avoid null parameters.
- No Raw Types: Always use generics; never use raw List or Map.
- No Old Switch: Use switch expressions (->); avoid fall-through.
- No Manual get/set: Use Records or value objects instead.
- No synchronized blocks: Use java.util.concurrent or Virtual Threads instead.
References
Canonical response anchors
When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:
- DTOs/Value Objects
- Lombok
- exhaustive switch
- if/else chains
- sealed interface/class
Files
3- SKILL.md
a3a1d022a22.4 KB - evals/evals.json
2c176213e92.8 KB - references/example.md
6697b5bc212.0 KB
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