java-classpath-search

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Use when you need to find which JAR contains a Java class, resolve import statements, identify classpath conflicts, or discover which dependency provides a class. Accepts fully qualified class names, simple class names, or partial patterns.

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Sourcequarkusio/quarkusdev-skills

Added on2026-04-10

NPX Install

npx skill4agent add quarkusio/quarkusdev-skills java-classpath-search

SKILL.md Content

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Java Classpath Search

Fast search across all Maven dependencies to find which JARs contain a Java class.

Overview

This skill searches a pre-built index of all classes in your Maven local repository, providing instant results for classpath queries. It's essential for resolving imports, debugging classpath conflicts, and discovering dependency sources.

When to Use

Finding which dependency provides a class
Resolving "class not found" errors
Checking for version conflicts (multiple JARs with same class)
Discovering available implementations of an interface
Understanding your project's dependency tree
Verifying a dependency is in your local Maven repo

Quick Reference

Search patterns:

Fully qualified:

com.fasterxml.jackson.databind.ObjectMapper

Simple name:
```
ObjectMapper
```
Partial pattern:
```
jackson.ObjectMapper
```

Index location:

$HOME/.cache/quarkusdev-skills/class-index.txt

Index refresh: Automatic if missing or older than 7 days

Implementation

Step 1: Determine Search Pattern

Parse the user input (available as

$ARGUMENTS

):

Input	Pattern Conversion
`com.fasterxml.jackson.databind.ObjectMapper`	`com/fasterxml/jackson/databind/ObjectMapper.class`
`ObjectMapper`	`/ObjectMapper.class` (any path ending with this)
`jackson.ObjectMapper`	`jackson/ObjectMapper.class`

Step 2: Ensure Index is Available

The class index is a tab-separated file mapping class paths to JAR paths.

bash

INDEX="$HOME/.cache/quarkusdev-skills/class-index.txt"

# Check if index needs rebuilding (missing or older than 7 days)
if [ ! -f "$INDEX" ] || [ $(find "$INDEX" -mtime +7 2>/dev/null | wc -l) -gt 0 ]; then
  # Dispatch index rebuild as subagent (can take 30-60 seconds)
  # Use Agent tool with prompt:
  # "Run the build-class-index.sh script from this skill directory
  #  Report when indexing is complete."

  # Wait for subagent to complete before continuing
fi

Note: Index building is dispatched to a subagent to keep the main conversation responsive. The script uses 8 parallel workers and typically completes in under 60 seconds.

Step 3: Search the Index

Search is instant (just grep on a text file):

For fully qualified class name:

bash

grep "com/fasterxml/jackson/databind/ObjectMapper\.class" "$INDEX"

For simple class name:

bash

grep -i "/ObjectMapper\.class" "$INDEX"

For partial pattern:

bash

grep -i "jackson.*ObjectMapper\.class" "$INDEX"

Step 4: Check Local Build Output

Also search project build directories for classes:

bash

find . -path "*/target/classes/*ClassName.class" 2>/dev/null

Step 5: Present Results

Format output to show:

Class path within JAR - The full package path
JAR file path - Highlight groupId, artifactId, version from path

Maven coordinates - Extract from JAR path:

~/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.15.0/jackson-databind-2.15.0.jar

Becomes:

com.fasterxml.jackson.core:jackson-databind:2.15.0

Conflict warnings - If multiple versions exist, flag as potential classpath issue

Example output format:

Found in 2 locations:

1. com/fasterxml/jackson/databind/ObjectMapper.class
   JAR: com.fasterxml.jackson.core:jackson-databind:2.15.0
   Path: ~/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.15.0/jackson-databind-2.15.0.jar

2. com/fasterxml/jackson/databind/ObjectMapper.class
   JAR: com.fasterxml.jackson.core:jackson-databind:2.14.2
   Path: ~/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.14.2/jackson-databind-2.14.2.jar

⚠️  WARNING: Multiple versions detected - potential classpath conflict

Step 6: Handle No Results

If search returns nothing:

Rebuild index - Run the build-class-index.sh script from this skill directory
Check spelling - Suggest corrected class name
Verify dependency - Class might not be in local repo, suggest
```
mvn dependency:resolve
```
Broaden search - Try searching for just the class name without package

Index Details

What's indexed:

All
```
.class
```
files in
```
~/.m2/repository/**/*.jar
```

Excludes:

-sources.jar

,

-javadoc.jar

,

-tests.jar

,

-test-*.jar

Excludes: Inner classes (
```
$
```
),
```
module-info
```
,
```
package-info
```

Index format:

com/example/MyClass.class\t/path/to/artifact-1.0.0.jar

Build time: ~30-60 seconds with 8 parallel workers

Size: Varies by repository size (typically 5-20 MB)

Tips

Index is automatically refreshed every 7 days
For inner classes, search JAR directly:
```
jar tf /path/to.jar | grep ClassName
```
Use
```
-i
```
flag for case-insensitive searches
The index uses 8 parallel workers for fast building
Subagent dispatch keeps main conversation responsive during index builds

Supporting Tool

The index is built by

build-class-index.sh

(included in this skill directory):

bash

#!/bin/bash
INDEX_FILE="${1:-$HOME/.cache/quarkusdev-skills/class-index.txt}"
REPO_DIR="${2:-$HOME/.m2/repository}"

find "$REPO_DIR" -name "*.jar" \
  -not -name "*-sources*" \
  -not -name "*-javadoc*" \
  -not -name "*-tests*" \
  -not -name "*-test-*" | \
  xargs -P 8 -I{} sh -c '
    jar tf "$1" 2>/dev/null | grep "\.class$" | grep -v "module-info\|package-info" | while read cls; do
      printf "%s\t%s\n" "$cls" "$1"
    done
  ' _ {} > "$INDEX_FILE"

Platform Notes

This skill works with:

Claude Code: Direct execution via Bash/Agent tools
Gemini CLI: Use equivalent bash/file tools
Codex: Use RunBash/SubAgent equivalents

The

build-class-index.sh

script is platform-independent (standard bash).

java-classpath-search

NPX Install

Tags

SKILL.md Content

Java Classpath Search

Overview

When to Use

Quick Reference

Implementation

Step 1: Determine Search Pattern

Step 2: Ensure Index is Available

Step 3: Search the Index

Step 4: Check Local Build Output

Step 5: Present Results

Step 6: Handle No Results

Index Details

Tips

Supporting Tool

Platform Notes