java-development

A set of guidelines for developing and reviewing Java programs and other projects that run on the Java Virtual Machine (JVM). It covers build tools, frameworks, tests, design, security, dependencies, and version upgrades.

In plain words
What is it for?
Use it for Java libraries, command-line tools, Maven or Gradle builds, Spring Boot, database code, tests, reviews, refactoring, and Java upgrades.
Why use it?
It helps an agent first understand an existing Java project's setup and conventions before suggesting changes or adding technologies.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/zander-zyx/java-development-skill/java-development-skill
Any agent
npx skills add zander-zyx/java-development-skill --skill java-development-skill
Clone the repo
git clone --depth 1 https://github.com/zander-zyx/java-development-skill

Made for: Claude Code, Codex.

Per session 102 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,139 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What 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.

ModelPer sessionOnce invoked
Fable 5 $0.00102 $0.02139
Opus 5 $0.00051 $0.01069
Sonnet 5 $0.00020 $0.00428
Haiku 4.5 $0.00010 $0.00214

Measured yesterday against content hash 0e39364a0e0e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

java-development 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 yesterday.

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.

SKILL.md · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Java Development Agent

Router skill for general Java/JVM work. Treat Spring Boot as one supported framework, not the default for every project. Load only the matching rule files below.

Defaults

  • Output explanations in Chinese when the user uses Chinese; keep code unchanged unless editing.
  • First identify the current project's runtime, Java version, build tool, framework, test stack, and conventions. Existing evidence beats this skill's defaults.
  • Do not introduce Spring Boot, Maven, Gradle, Lombok, MyBatis-Plus, JPA, Testcontainers, or Java 17+ syntax unless the project already uses it or the user asks.
  • If creating a new project and no preference is given: choose a dependency-supported Java LTS baseline (17 or newer), infer Maven or Gradle from the surrounding repository, use JUnit 5, constructor-based design, SLF4J-compatible logging, and immutable DTOs where practical.
  • For a new Spring Boot project, verify the current stable release, Java/build requirements, and third-party starter compatibility from official sources before choosing a line. For existing projects, keep their supported line unless migration is requested.
  • Do not choose a persistence framework by geography or popularity. Preserve the existing choice; for greenfield work, select JDBC, jOOQ, MyBatis/MyBatis-Plus, or JPA/Hibernate from the actual query model and team constraints.
  • Prefer constructor injection in DI frameworks. Use Lombok (@RequiredArgsConstructor, @Slf4j) only when the project already uses Lombok; otherwise write explicit constructors/loggers.
  • If multiple modules or frameworks exist, modify only the affected module unless the user asks for a cross-cutting change.
  • Do not edit generated output unless explicitly requested; edit the source template, annotation processor input, schema, or generator configuration instead.

Loading Rules

Start with the smallest useful set:

  • Any Java task: load core/java-general-development.md only if project classification or default choice is unclear.
  • API/exception/version work: load the specific core/... rule before framework rules.
  • Build edits: load exactly one build rule (build-tools/...) matching the detected build tool.
  • Spring Boot edits: load the primary spring-boot/... rule only when the project actually uses Spring Boot.
  • Broad code review: start with code-review/cr-anti-patterns.md, then add specific risk files.
  • Test work: load testing/test-layering.md first, then the framework-specific test file.
  • JVM incident: load the symptom file first; add GC/thread/resource files only when evidence points there.
  • Do not load README files or examples/ unless the user asks for usage docs.

Read the full file on GitHub · 87 lines

Changes

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.

  1. yesterday First seen · 87 lines · 102 tokens per session scan A 0e39364a0e0e

Subscribe to this mod's changes

java-development is a skill published in the GitHub repository zander-zyx/java-development-skill (5 stars, last pushed 1mo ago), licensed MIT. It adds 102 tokens to every session and 2,139 once invoked, about $0.0005 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.