Class Finder Tool Introduction

Java Class-Path tells Java where to look on the file system for files defining these classes. For generic java application, all class files are searched/loaded from the jar files, or class folders, based on these path item sequence.

Usually, the developer would like to find class in one or many jar files, like the following situation,

• Know which class is loaded, if same class name hosted in different jar files;
• List all duplicated class names to eliminate incorrect class loading issue;
• Find class full name based on specified Simple class name or name with wild card character;
• List some class with specified constant string;
• List classes that using other class, method or field;

The classfinder library/tool is helping Java developer to find class easily inside or outside JVM without source code provided. This manual is mainly to introduce the core function for this tool running as standalone application from command line.

NOTE: It only supports Java 8+ (including Java 11). For prior Java version, please download classfinder v1.2.2 from https://github.com/feng-zh/classfinder/releases/download/v1.2.2/classfinder.jar

Download

Download classfinder latest version (Java 8+ is required) from https://jitpack.io/com/github/feng-zh/classfinder/v2.1.0/classfinder-v2.1.0-jar-with-dependencies.jar

Basic Usage

Run in Command-Line

The classfinder support two ways by specifying jar files.

• Add jar files as parameter -classpath

  java -jar classfinder.jar -classpath file1.jar;file2.jar;file3.jar NameToSearch

• Use jar file list from Std in (or pipeline)

  dir /b path\to\folder\*.jar | java -jar classfinder.jar NameToSearch

  or recursive search from current work directory by enabling /s option

  dir /b /s *.jar | java -jar classfinder.jar NameToSearch

  or more powerful command find in Unix/Linux

  find /path/to/folder -name "*.jar" | java -jar classfinder.jar NameToSearch

To know which jar files are involved, use "-verbose" parameter to enable file list:

$ find /path/to/folder -name "*.jar" | java -jar classfinder.jar -verbose NameToSearch1 NameSearch2 
***** START CLASSPATH ***** 
/path/to/folder/file1.jar 
/path/to/folder/file2.jar 
/path/to/folder/sub/file3.jar 
***** END CLASSPATH ***** 

***** START ARGUMENTS ***** 
NameToSearch1 
NameToSearch2 
***** END ARGUMENTS ***** 

Display Full Class Name and File Location

The command can display full class name by specify simple class name, or with wild card character. The candidate full class name list, with the source file name will be shown. If same class find different jar files, the file name will be displayed by sequence of path order.

C:\> dir /b *.jar | java -jar classfinder.jar String 
[com.sun.org.apache.xpath.internal.operations.String] 
C:\Program Files (x86)\Java\jre6\lib\rt.jar 
[java.lang.String] 
C:\Program Files (x86)\Java\jre6\lib\rt.jar 

In addition, a switch flag -group can group result by jar file name.

C:\> dir /b *.jar | java -jar classfinder.jar -group Util* 
-- From [C:\classfinder.jar] 
Util 
... 
Util$SuffixFilter 
-- From [C:\rt.jar] 
com.sun.corba.se.impl.javax.rmi.CORBA.Util 
com.sun.corba.se.impl.javax.rmi.CORBA.Util$1 
... 
sun.rmi.server.Util 
sun.text.normalizer.Utility 

Find Duplicate Classes

To list duplicate class by its simple name, or wild card names, use -duplicate parameter with name parameter can list all duplicated class. The jar file name is listed by its path order, which means the effective one is in the first.

C:\>dir /b *.jar | java -jar classfinder.jar -duplicate Util* 
[Util] 
C:\classfinder-dup.jar 
C:\classfinder.jar 
... 
[Util$SuffixFilter] 
C:\classfinder-dup.jar 
C:\classfinder.jar 

List Class under Package Name

All class under the specified package (and its sub-packages) can be displayed over all jar files with -package parameter and name parameter.

C:\>dir /b *.jar | java -jar classfinder.jar -package java.lang 
-- Class in package [java.lang] 
java.lang.StackTraceElement 
java.lang.ApplicationShutdownHooks$1 
java.lang.StrictMath 
... 

Class Relationship Usage

List Super Class Chain (Up Hierarchy)

To see all super class and interface names for the specified class, use -super parameter and full class name.

C:\>dir /b *.jar | java -jar classfinder.jar -super java.util.Properties 
-- Super class for [java.util.Properties] 
java.util.Hashtable 
java.util.Dictionary 
java.lang.Object 
java.io.Serializable 
java.lang.Cloneable 
java.util.Map 

List Sub-Classes (Down Hierarchy)

To see all sub class or interface names for the specified class, use -sub parameter and full class name.

C:\>dir /b *.jar | java -jar classfinder.jar -super java.util.Properties 
-- Sub class for [java.util.Properties] 
com.sun.security.sasl.Provider 
java.security.AuthProvider 
java.security.Provider 
... 
sun.security.smartcardio.SunPCSC 

List Incoming Referring Classes (References)

To get reference of the specified class over the jar files, use -ref parameter and full class name can provide all class which depends on this class.

C:\>dir /b *.jar | java -jar classfinder.jar -ref java.lang.Shutdown 
-- Reference class for [java.lang.Shutdown] 
java.lang.ApplicationShutdownHooks 
java.lang.Runtime 
java.lang.Shutdown 
java.lang.Shutdown$1 
java.lang.Shutdown$Lock 
java.lang.System$2 
java.lang.Terminator$1 

List Outgoing Depending Classes

Also to know all depending classes over the jar files, use -depend parameter and full class name can provide all class which used by this class. That means if no such class in classpath, it may trigger class not found error.

The result shows existing dependence class name, and non-founded dependence class names (some may related to JRE).

C:\>dir /b *.jar | java -jar classfinder.jar -depend Util 
-- Dependence class for [Util] 
AbstractClassFinder 
ClassFinder 
ClassLoaderFinder 
... 
-- Non-founded dependence class for [Util] 
com.sun.org.apache.bcel.internal.classfile.Attribute 
com.sun.org.apache.bcel.internal.classfile.ClassParser 
... 

List Incoming Referring Classes for Method (Caller List)

To get reference of the specified method in the class, use -mref parameter and full method with class name can provide related class name list.

C:\>dir /b *.jar | java -jar classfinder.jar -mref java.lang.System.exit 
-- Reference class for Method [java.lang.System.exit] 
ClassPathFinderMain 
JarCat 
com.sun.corba.se.impl.activation.Quit 
com.sun.corba.se.impl.activation.ServerMain 
com.sun.corba.se.impl.naming.cosnaming.TransientNameServer 
... 

List Incoming Referring Classes for Field (Access List)

To get reference of the specified field in the class, use -fref parameter and full field with class name can provide related class name list.

C:\>dir /b *.jar | java -jar classfinder.jar -fref java.lang.System.out 
-- Reference class for Field [java.lang.System.out] 
ClassPathFinderMain 
JarCat 
... 

Other Usage

List Class containing String Text

During some application running, if want to know where the log string is created, we can first use -strings to find possible class, then look into them (or source code) by using other tools.

C:\>dir /b *.jar | java -jar classfinder.jar -strings "Options:" 
-- Class contains text "Options:" 
[com.sun.servicetag.Installer] 
Internal Options: 
[sun.tools.jar.resources.jar] 
Usage: jar {ctxui}[vfm0Me] [jar-file] [manifest-file] [entry-point] [-C dir] files ... 
Options: 
... 

Display Text File Content

If the jar file contains some property file, XML file, or java source file, use -cat parameter can help to view its text directly without extracting them.

C:\>dir /b *.jar | java -jar classfinder.jar -cat ClassFinder 
::[1] com/hp/it/gadsc/et/ei/tools/classfinder/ClassFinder.class 
::Warn: "com/hp/it/gadsc/et/ei/tools/classfinder/ClassFinder.class" is not a text file, may be content type of application/java-vm 
::[2] com/hp/it/gadsc/et/ei/tools/classfinder/ClassFinder.java 
package com.hp.it.gadsc.et.ei.tools.classfinder; 

import java.net.URL; 
import java.util.List; 
import java.util.Map; 

public interface ClassFinder { 
... 

Full Option

Here are the full usage for reference. Type java -jar classfinder.jar or incorrect parameter can also print these information in console.

Usage: classfinder [SCOPE] [OPTION] NAME... 
Find class name from classpath. 

SCOPE: 
-classpath <PATH LIST> [-jre <JAVA HOME>] 
Lookup class from the provided class path 
(EMPTY) 
Find class from the class path loaded from std in. It accept path separator or new line separator 

OPTION: 
(EMPTY) 
List class names and group by name 
-group 
Group class by its source 
-package 
List class names by package name, which is specified in NAME 
-super 
List all super class or interface names 
-sub 
List all children class or interface names 
-duplicate 
List all duplicated class or interface names 
-ref 
List all incoming referring class or interface names 
-mref 
List all incoming referring class or interface names for the full method name 
-fref 
List all incoming referring class or interface names for the full field name 
-depend 
List all outgoing depending class or interface names 
-strings 
List class or interface contains the string text 
-cat 
Print text file with name matching the string text 
-verbose 
List class path will be searched 
-current 
Add current java home into classpath if no explicit java home specified 

NAME: 
java.lang.Object The full class name 
'Object*' The class name with wildcards, but without package name. 
This is only support for class name finding. 
'java.util.*List' The full class name with wildcards(like '*', or '?'). This is only support for class name finding. 
'java.util.Collection.toArray' The full method name. This is only support for method name based finding. 
'java.lang.System.out' The full field name. This is only support for field name based finding.