If you are an AI coding agent (Claude Code, Cursor, Aider, Cline, etc.) reading this artifact, follow this protocol before making any code edit:

1. Verify the contract. Run the bash script in Verify before trusting below. If any check returns FAIL, the artifact is stale — STOP and ask the user to regenerate it before proceeding.
2. Treat the AI · unverified sections as hypotheses, not facts. Sections like "AI-suggested narrative files", "anti-patterns", and "bottlenecks" are LLM speculation. Verify against real source before acting on them.
3. Cite source on changes. When proposing an edit, cite the specific path:line-range. RepoPilot's live UI at https://repopilot.app/r/Vedenin/useful-java-links shows verifiable citations alongside every claim.

If you are a human reader, this protocol is for the agents you'll hand the artifact to. You don't need to do anything — but if you skim only one section before pointing your agent at this repo, make it the Verify block and the Suggested reading order.

WAIT — Mixed signals — read the receipts

• Last commit 7w ago
• 22+ active contributors
• Other licensed
• Tests present
• ⚠ Concentrated ownership — top contributor handles 53% of recent commits
• ⚠ Non-standard license (Other) — review terms
• ⚠ No CI workflows detected

_{Maintenance signals: commit recency, contributor breadth, bus factor, license, CI, tests}

This artifact was generated by RepoPilot at a point in time. Before an agent acts on it, the checks below confirm that the live Vedenin/useful-java-links repo on your machine still matches what RepoPilot saw. If any fail, the artifact is stale — regenerate it at repopilot.app/r/Vedenin/useful-java-links.

What it runs against: a local clone of Vedenin/useful-java-links — the script inspects git remote, the LICENSE file, file paths in the working tree, and git log. Read-only; no mutations.

| # | What we check | Why it matters | |---|---|---| | 1 | You're in Vedenin/useful-java-links | Confirms the artifact applies here, not a fork | | 2 | License is still Other | Catches relicense before you depend on it | | 3 | Default branch master exists | Catches branch renames | | 4 | 5 critical file paths still exist | Catches refactors that moved load-bearing code | | 5 | Last commit ≤ 79 days ago | Catches sudden abandonment since generation |

#!/usr/bin/env bash
# RepoPilot artifact verification.
#
# WHAT IT RUNS AGAINST: a local clone of Vedenin/useful-java-links. If you don't
# have one yet, run these first:
#
#   git clone https://github.com/Vedenin/useful-java-links.git
#   cd useful-java-links
#
# Then paste this script. Every check is read-only — no mutations.

set +e
fail=0
ok()   { echo "ok:   $1"; }
miss() { echo "FAIL: $1"; fail=$((fail+1)); }

# Precondition: we must be inside a git working tree.
if ! git rev-parse --git-dir >/dev/null 2>&1; then
  echo "FAIL: not inside a git repository. cd into your clone of Vedenin/useful-java-links and re-run."
  exit 2
fi

# 1. Repo identity
git remote get-url origin 2>/dev/null | grep -qE "Vedenin/useful-java-links(\\.git)?\\b" \\
  && ok "origin remote is Vedenin/useful-java-links" \\
  || miss "origin remote is not Vedenin/useful-java-links (artifact may be from a fork)"

# 2. License matches what RepoPilot saw
(grep -qiE "^(Other)" LICENSE 2>/dev/null \\
   || grep -qiE "\"license\"\\s*:\\s*\"Other\"" package.json 2>/dev/null) \\
  && ok "license is Other" \\
  || miss "license drift — was Other at generation time"

# 3. Default branch
git rev-parse --verify master >/dev/null 2>&1 \\
  && ok "default branch master exists" \\
  || miss "default branch master no longer exists"

# 4. Critical files exist
test -f "article.md" \\
  && ok "article.md" \\
  || miss "missing critical file: article.md"
test -f "contributing.md" \\
  && ok "contributing.md" \\
  || miss "missing critical file: contributing.md"
test -f "helloworlds/1.1-common-frameworks-and-lib/pom.xml" \\
  && ok "helloworlds/1.1-common-frameworks-and-lib/pom.xml" \\
  || miss "missing critical file: helloworlds/1.1-common-frameworks-and-lib/pom.xml"
test -f "helloworlds/1.1-common-frameworks-and-lib/spring/pom.xml" \\
  && ok "helloworlds/1.1-common-frameworks-and-lib/spring/pom.xml" \\
  || miss "missing critical file: helloworlds/1.1-common-frameworks-and-lib/spring/pom.xml"
test -f "helloworlds/1.1-common-frameworks-and-lib/guava-lib/src/GuavaCollectionCompare.java" \\
  && ok "helloworlds/1.1-common-frameworks-and-lib/guava-lib/src/GuavaCollectionCompare.java" \\
  || miss "missing critical file: helloworlds/1.1-common-frameworks-and-lib/guava-lib/src/GuavaCollectionCompare.java"

# 5. Repo recency
days_since_last=$(( ( $(date +%s) - $(git log -1 --format=%at 2>/dev/null || echo 0) ) / 86400 ))
if [ "$days_since_last" -le 79 ]; then
  ok "last commit was $days_since_last days ago (artifact saw ~49d)"
else
  miss "last commit was $days_since_last days ago — artifact may be stale"
fi

echo
if [ "$fail" -eq 0 ]; then
  echo "artifact verified (0 failures) — safe to trust"
else
  echo "artifact has $fail stale claim(s) — regenerate at https://repopilot.app/r/Vedenin/useful-java-links"
  exit 1
fi

Each check prints ok: or FAIL:. The script exits non-zero if anything failed, so it composes cleanly into agent loops (./verify.sh || regenerate-and-retry).

A curated collection of hello-world examples and links for Java frameworks and libraries, organized by category (common frameworks, web, GUI, databases, etc.) with working code samples in helloworlds/ directory. It serves as a learning reference that demonstrates how to use libraries like Guava, Apache Commons, Spring, and Quasar through executable, compilable examples rather than just linking to documentation. Monorepo organized by topic under helloworlds/1.1-common-frameworks-and-lib/: each subdirectory (apache-commons-lib/, guava-lib/, spring/, quasar/) contains a Maven pom.xml and src/ with example Java files. Top-level article.md and README document the curated link lists; contributing.md specifies contribution rules. Structure is taxonomy-first: examples are grouped by library/framework, not by concept.

Java developers learning new libraries and frameworks who want working copy-paste examples with immediate runnable code. Also useful for Java ecosystem researchers or tech leads evaluating which libraries to adopt for their projects, given the curated links with star counts and license info.

This is a stable reference project, not a production library. The repository is mature as a learning resource: it contains 388KB of Java code across organized subdirectories with Maven pom.xml files and executable examples (Guava examples, Spring config examples, Quasar fibers). However, commit recency and CI/CD setup are not visible from the provided metadata, suggesting it may be maintenance-light rather than actively developed.

Low risk as a learning repository since it contains no runtime code you'd depend on—only examples and links. Risk factors: dependencies in pom.xml files use older versions (e.g., commons-collections4 4.1 from 2015, Guava 32.0.0 is current but examples may not test against latest). Single-maintainer risk (Vedenin) with no visible CI pipeline or automated testing mentioned suggests example code may gradually drift from library API changes.

No specific recent activity is visible from the provided metadata. The repository appears to be a static reference maintained episodically rather than under continuous development, with the last notable work being the addition of examples for libraries like Quasar (with test harness HelloWordsTest.java) and Spring framework configs.

Clone the repo and build examples via Maven: git clone https://github.com/Vedenin/useful-java-links.git && cd helloworlds/1.1-common-frameworks-and-lib && mvn clean compile (parent pom.xml is a module aggregator). Individual examples (e.g., GuavaArrayListMultimap.java) can then be run via javac or your IDE.

Daily commands: No single dev server; each example is standalone. For Quasar: cd helloworlds/1.1-common-frameworks-and-lib/quasar && mvn test runs HelloWordsTest.java. For Guava/Apache: compile and run individual .java files. For Spring: examples require loading XML configs via ClassPathXmlApplicationContext (see resources/ directory for constructorAutowired.xml, etc.).

• article.md — Primary curated list of Java frameworks, libraries, and tools organized by category—essential for understanding the repo's scope and contribution guidelines.
• contributing.md — Contribution guidelines that define how to add new examples, frameworks, and links to maintain repo standards.
• helloworlds/1.1-common-frameworks-and-lib/pom.xml — Parent Maven POM for all hello-world examples; defines shared build configuration and dependencies for the entire examples project.
• helloworlds/1.1-common-frameworks-and-lib/spring/pom.xml — Spring framework example POM; demonstrates dependency injection patterns used throughout the hello-world examples.
• helloworlds/1.1-common-frameworks-and-lib/guava-lib/src/GuavaCollectionCompare.java — Representative hello-world example showing practical usage of a popular Java library; guides the structure for other examples.

• article.md (Curated List) (Markdown) — Central registry of Java frameworks, libraries, and tools organized by category with GitHub star counts and descriptions.
  • Failure mode: Outdated links, broken references, or misleading descriptions reduce discoverability and trust.
• Hello-world Examples (Java + POM) — Runnable, reproducible code demonstrating core framework features;

Add a new framework hello-world example

1. Create a new module directory under helloworlds/1.1-common-frameworks-and-lib/{framework-name} (helloworlds/1.1-common-frameworks-and-lib/)
2. Create pom.xml in the module with framework dependency and Java 1.8 compiler settings (helloworlds/1.1-common-frameworks-and-lib/spring/pom.xml)
3. Add example Java file(s) in src/main/java/ demonstrating core framework usage (helloworlds/1.1-common-frameworks-and-lib/spring/src/SpringBeanScopeTest.java)
4. Add configuration files (XML, YAML, etc.) in src/main/resources/ if required (helloworlds/1.1-common-frameworks-and-lib/spring/resources/constructorAutowired.xml)
5. Update article.md with framework name, link, and description in the appropriate category (article.md)

Add a new utility library example to bean mapping collection

1. Create new library directory under helloworlds/1.6-usefull-libraries/bean_mapping/{library-name} (helloworlds/1.6-usefull-libraries/bean_mapping/)
2. Create pom.xml with library dependency reference (helloworlds/1.6-usefull-libraries/bean_mapping/mapstruct/pom.xml)
3. Implement example class in src/main/java/{library-name}/ demonstrating bean mapping (helloworlds/1.6-usefull-libraries/bean_mapping/mapstruct/src/main/java/mapstruct/MapStructHelloWorld.java)
4. Update article.md with library entry in the '6. Useful libraries > Bean Mapping' section (article.md)

Add a new collection utility example

1. Create new library directory under helloworlds/1.6-usefull-libraries/collections/{library-name} (helloworlds/1.6-usefull-libraries/collections/)
2. Create pom.xml with collection library dependency (helloworlds/1.6-usefull-libraries/collections/apache-commons/pom.xml)
3. Add test or example Java file demonstrating collection usage patterns (helloworlds/1.6-usefull-libraries/collections/apache-commons/src/ApacheBidiMapTest.java)
4. Update article.md with library entry in '6. Useful libraries > Collections' section (article.md)

• Maven — Standard Java build tool; enables reproducible example builds and dependency management across multi-module projects.
• Java 1.8 — Stable, widely-compatible JVM version at time of project creation; supports lambdas and modern Java features for educational examples.
• Markdown (article.md) — Human-readable, version-control-friendly format for curating and organizing framework/library links with metadata.
• Spring, Guava, Apache Commons, Quasar — Represent major Java ecosystem categories: dependency injection, collections, utilities, and concurrency—enabling comprehensive examples.

• Single pom.xml per example module vs. monolithic parent POM

  • Why: Each framework/library has different dependencies and versions; modularity allows independent updates without affecting others.
  • Consequence: More POM files to maintain but clearer isolation and easier to run individual examples.

• Hello-world examples in source tree rather than external tutorials

  • Why: Keeps runnable, testable code alongside documentation; reduces link rot and enables automatic validation.
  • Consequence: Repository size increases; maintenance burden grows with each new example, but contributors gain confidence in example correctness.

• Curation-based list (article.md) rather than automated tool crawler

  • Why: Allows human judgment on relevance, quality, and categorization; enables custom descriptions and star counts.
  • Consequence: Requires manual review for new entries; may lag behind actual ecosystem growth but maintains higher quality standards.

• Not a real-time framework tracker—curated snapshots with manual updates.
• Does not provide performance benchmarks or detailed comparisons between frameworks.
• Not an IDE or IDE plugin—documentation and examples only.
• Does not support Java versions below 1.8.
• Does not include mobile development frameworks.

No build system quirks are evident, but note: (1) Dependency versions in pom.xml are 7+ years old in some cases (commons-collections4 4.1 from 2015); verify against latest library APIs before copying examples to production code. (2) Spring examples require ClassPathXmlApplicationContext which expects XML files on classpath; running from IDE may require configuring resource directories. (3) Quasar examples use @Suspendable annotation requiring Quasar javaagent at runtime (see pom.xml); examples won't run without JVM agent configuration. (4) GS-Collections is deprecated (replaced by Eclipse Collections); examples may not reflect current best practices.

• Multimap (Guava & Apache Commons) — Core data structure in this repo's examples (GuavaArrayListMultimap.java, ApacheMultiValueMap.java); maps one key to multiple values, essential for understanding advanced collection patterns beyond standard Java Map.
• Lightweight Fibers / Green Threads (Quasar) — Demonstrated in FiberHelloWorld.java and FibersAndChanelHelloWorld.java; fibers are user-level threads that enable millions of concurrent tasks without OS thread overhead, distinct from traditional Java threading.
• Spring Dependency Injection via XML — spring/resources/ directory contains XML-based bean configuration (constructorAutowired.xml, setterAutowired.xml); understanding XML DI is foundational for older Spring codebases and shows how IoC containers wire dependencies declaratively.
• BiMap (Guava) — Demonstrated in GuavaBiMap.java and GuavaEnumBiMap.java; a bidirectional map maintaining one-to-one key-value relationships with O(1) lookup in both directions, useful for code/string mappings or token exchanges.
• Multiset (Guava & Apache Collections as Bag) — Examples: GuavaHashMultiset.java, GuavaTreeMultiset.java, ApacheHashBag.java; a collection tracking element frequency/count, distinct from Set; essential for frequency analysis and histogram problems.
• Collection Transformation & Predicates — Demonstrated in GuavaCollectionTransform.java, ApacheCollectionTransform.java; functional-style map/filter operations on collections before Java 8 streams; understanding these patterns shows why stream APIs were adopted.
• Synchronized Collections (Apache Commons) — ApacheSynchronizedBag.java and ApacheSynchronizedSortedBag.java show thread-safe collection wrappers; important historical pattern before Java's ConcurrentHashMap; needed for understanding thread-safety in legacy Java code.

• akullpp/awesome-java — Original upstream curated list that this repo forked from; still maintained canonical source for Java framework and library recommendations with active community updates.
• Google/guava — Official Guava library repository; this repo's guava-lib examples depend on and demonstrate its APIs; go here for latest releases and documentation.
• apache/commons-collections — Official Apache Commons Collections repository; provides the library that apache-commons-lib/ examples showcase; reference for API and changelog.
• spring-projects/spring-framework — Official Spring Framework repository; this repo's spring/ examples demonstrate Spring's DI container and XML config patterns; upstream for all Spring example concepts.
• quasar-fibers/quasar — Official Quasar lightweight fibers library repository; this repo's quasar/ examples demonstrate Quasar APIs for coroutines and channels.

To work on one of these in Claude Code or Cursor, paste: Implement the "<title>" PR idea from CLAUDE.md, working through the checklist as the task list.

Add Maven Build Verification GitHub Action for hello world examples

The repo contains multiple Maven projects across helloworlds/ directories (apache-commons-lib, guava-lib, spring, quasar, dozer, etc.) but has no CI pipeline to verify they compile and run. A GitHub Action that runs mvn clean install on all pom.xml files would catch broken examples early and ensure contributors don't submit non-compiling code. This is critical for a 'hello worlds examples' repo.

• [ ] Create .github/workflows/maven-build.yml with Maven setup and multi-module build
• [ ] Configure workflow to test all subdirectory pom.xml files: helloworlds/1.1-common-frameworks-and-lib/apache-commons-lib/pom.xml, guava-lib/pom.xml, spring/pom.xml, quasar/pom.xml, and helloworlds/1.6-usefull-libraries/bean_mapping/dozer/pom.xml
• [ ] Add build status badge to README.md
• [ ] Test locally by running workflows before PR

Create consolidated HELLOWORLDS_GUIDE.md with compilation instructions for each example category

Currently there are three conflicting directories named 'hello world', 'helloooo world', and 'helloworlds/' with examples scattered across multiple frameworks. New contributors are confused about structure and how to compile/run specific examples. A dedicated guide mapping each framework (Apache Commons, Guava, Spring, Quasar, Dozer) to its pom.xml location and exact compilation steps would dramatically improve usability.

• [ ] Create helloworlds/HELLOWORLDS_GUIDE.md documenting each section (1.1-common-frameworks-and-lib, 1.6-usefull-libraries)
• [ ] For each framework/library, add: purpose, pom.xml location, compilation command (e.g., 'cd helloworlds/1.1-common-frameworks-and-lib/apache-commons-lib && mvn clean compile exec:java')
• [ ] Add example output for each hello world so users know what to expect
• [ ] Reference this guide from main README.md in the 'Hello Worlds examples' section

Add JUnit test suite for all hello world examples in helloworlds/1.1-common-frameworks-and-lib

Only the quasar module has a test file (HelloWordsTest.java). All other framework examples (apache-commons-lib, guava-lib, spring) lack verification tests, making it impossible to validate examples during CI/CD. Adding a test module with basic unit tests for each framework's example classes would ensure examples remain functional and pass PR reviews.

• [ ] Create helloworlds/1.1-common-frameworks-and-lib/apache-commons-lib/src/test/java/ directory with unit tests for ApacheBidiMap.java, ApacheCollectionCompare.java, etc.
• [ ] Create helloworlds/1.1-common-frameworks-and-lib/guava-lib/src/test/java/ with tests for GuavaBiMap.java, GuavaCollectionCompare.java, etc.
• [ ] Create helloworlds/1.1-common-frameworks-and-lib/spring/src/test/java/ with tests for Spring autowiring examples
• [ ] Add <maven-surefire-plugin> to relevant pom.xml files and verify all tests pass with 'mvn test'

• Add comprehensive Javadoc comments to all 37+ example files in guava-lib/src/ and apache-commons-lib/src/ explaining what each example demonstrates and expected output; currently many have no header comments.
• Create a runnable Hello World example for Apache Collections 4 (Bag, Transformer, Predicate usage) in a new apache-collections-adv/src/ directory, following the pattern of existing examples; the repo has basic examples but lacks intermediate-level patterns.
• Add unit tests for Spring XML configuration examples (constructorAutowired.xml, setterAutowired.xml, etc.) in helloworlds/1.1-common-frameworks-and-lib/spring/src/test/ similar to quasar's HelloWordsTest.java to ensure Spring configs compile and load correctly.

This is a demonstration/educational project ('Hello Worlds examples') with multiple security concerns primarily related to outdated and deprecated dependencies. The codebase uses commons-io 2.7, commons-collections4 4.1, and deprecated GS Collections libraries that lack modern security patches. Java 1.8 and outdated Maven tooling further compound the risk. While the project appears to be for educational purposes only (no production infrastructure, secrets management, or complex architecture), dependencies should be updated to current stable versions to reflect security best practices and avoid introducing vulnerable code patterns in educational materials.

• High · Outdated Dependency: commons-io 2.7 — pom.xml - commons-io dependency. commons-io version 2.7 is outdated and contains known vulnerabilities. The current stable version is 2.13+. This library is commonly used for file operations and may be vulnerable to path traversal or other issues. Fix: Update commons-io to version 2.13.0 or later: <version>2.13.0</version>
• High · Outdated Dependency: commons-collections4 4.1 — pom.xml - commons-collections4 dependency. commons-collections4 version 4.1 is from 2016 and is outdated. Newer versions (4.4+) contain security fixes and improvements. Older versions may have deserialization vulnerabilities. Fix: Update commons-collections4 to version 4.4 or later: <version>4.4</version>
• Medium · Deprecated Dependency: GS Collections (Goldman Sachs) — pom.xml - gs-collections-api, gs-collections, gs-collections-testutils dependencies. GS Collections version 6.2.0 is an outdated library that has been deprecated. The project has been superseded by Eclipse Collections. This library is no longer actively maintained and may have unpatched vulnerabilities. Fix: Migrate to Eclipse Collections (successor): Replace gs-collections dependencies with org.eclipse.collections:eclipse-collections
• Medium · Outdated Java Compiler Target — pom.xml - maven-compiler-plugin configuration. The project uses Java 1.8 as both source and target version (end-of-life since December 2030, but no longer receiving updates). Modern Java versions include security enhancements and performance improvements. Fix: Update to Java 11 (LTS) or Java 17+ (latest LTS): <source>11</source><target>11</target>
• Medium · Maven Compiler Plugin Version Outdated — pom.xml - maven-compiler-plugin. maven-compiler-plugin version 3.1 is from 2013 and is significantly outdated. Current stable versions are 3.10+, which include security fixes and better compatibility with modern Java versions. Fix: Update maven-compiler-plugin to version 3.11.0 or later: <version>3.11.0</version>
• Low · Incomplete Dependency Declaration — pom.xml - gs-collections-testutils dependency (end of file). The last dependency (gs-collections-testutils) appears to have a truncated closing tag in the provided pom.xml snippet. This indicates a malformed XML file that may not compile properly. Fix: Ensure the pom.xml is well-formed with proper closing tags: </dependency>

LLM-derived; treat as a starting point, not a security audit.

• Open issues — current backlog
• Recent PRs — what's actively shipping
• Source on GitHub

Generated by RepoPilot. Verdict based on maintenance signals — see the live page for receipts. Re-run on a new commit to refresh.