Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/jabrena/cursor-rules-examples/143-java-functional-exception-handlingnpx skills add jabrena/cursor-rules-examples --skill 143-java-functional-exception-handlinggit clone --depth 1 https://github.com/jabrena/cursor-rules-examplesWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00080 | $0.00579 |
| Opus 5 | $0.00040 | $0.00290 |
| Sonnet 5 | $0.00016 | $0.00116 |
| Haiku 4.5 | $0.00008 | $0.00058 |
Grade A, and why
143-java-functional-exception-handling scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 45 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Java Functional Exception handling Best Practices
Identify and apply functional exception handling best practices in Java to improve error clarity, maintainability, and performance by eliminating exception overuse in favour of monadic error types.
What is covered in this Skill?
Optional<T>for nullable values over throwingNullPointerExceptionorNotFoundException- VAVR
Either<L,R>for predictable business-logic failures CompletableFuture<T>for async error handling- Sealed classes and records for rich error type hierarchies with exhaustive pattern matching
- Enum-based error types for simple failure cases
- Functional composition:
flatMap/map/peek/peekLeftfor chaining operations that can fail - Structured logging: warn/info for business failures, error for system failures
- Checked vs unchecked exception discipline
- Exception chaining with full causal context when exceptions are unavoidable
Scope: The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.
Constraints
Before applying any functional exception handling changes, ensure the project validates. When introducing Either types, confirm the VAVR dependency (io.vavr:vavr) and SLF4J are present.
- MANDATORY: Run
./mvnw validateormvn validatebefore applying any changes - SAFETY: If validation fails, stop immediately — do not proceed until the project is in a valid state
- DEPENDENCY: When introducing
Eithertypes, confirm VAVR (io.vavr:vavr) and SLF4J are present - VERIFY: Run
./mvnw clean verifyormvn clean verifyafter applying improvements - BEFORE APPLYING: Read the reference for detailed good/bad examples, constraints, and safeguards for each functional exception handling pattern
When to use this skill
- Review Java code for functional exception handling
- Apply best practices for functional exception handling in Java code
Reference
For detailed guidance, examples, and constraints, see references/143-java-functional-exception-handling.md.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 3d ago First seen · 45 lines · 80 tokens per session scan A f8dd4745295c
143-java-functional-exception-handling is a skill published in the GitHub repository jabrena/cursor-rules-examples (2 stars, last pushed 7d ago), licensed Apache-2.0. It adds 80 tokens to every session and 579 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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