Java LanguageSAFE

A collection of Agent Skills Standard and Best Practice for Programming Languages, Frameworks that help our AI Agent follow best practies on frameworks and programming laguages

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: java-language
description: 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.
metadata:
  triggers:
    files:
    - '**/*.java'
    - 'pom.xml'
    - 'build.gradle'
    keywords:
    - record
    - sealed
    - switch
    - var
    - Optional
    - stream
    - VirtualThread
    - instanceof
    - text block
---
# 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 **`var`** for 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 **`instanceof`** with 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()`**, and **`Set.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

- [Records, Pattern Matching & Virtual Threads](references/example.md)

## 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

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (0)

No findings outside the package's declared scope.

Gates applied: no_behavioural_pass.