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Download and Run JPlag

Download a released version - all releases are single-JAR releases.

Type java -jar jplag-yourVersion.jar in a console to see the command line options. The options as of 2019/03/20 are:

JPlag (Version 2.12.0-SNAPSHOT), Copyright (c) 2004-2019 KIT - IPD Tichy, Guido Malpohl, and others.
Usage: JPlag [ options ] [<root-dir>] [-c file1 file2 ...]
 <root-dir>        The root-directory that contains all submissions

options are:
 -v[qlpd]        (Verbose)
                 q: (Quiet) no output
                 l: (Long) detailed output
                 p: print all (p)arser messages
                 d: print (d)etails about each submission
 -d              (Debug) parser. Non-parsable files will be stored.
 -S <dir>        Look in directories <root-dir>/*/<dir> for programs.
                 (default: <root-dir>/*)
 -s              (Subdirs) Look at files in subdirs too (default: deactivated)

 -p <suffixes>   <suffixes> is a comma-separated list of all filename suffixes
                 that are included. ("-p ?" for defaults)

 -o <file>       (Output) The Parserlog will be saved to <file>
 -x <file>       (eXclude) All files named in <file> will be ignored
 -t <n>          (Token) Tune the sensitivity of the comparison. A smaller
                 <n> increases the sensitivity.
 -m <n>          (Matches) Number of matches that will be saved (default:20)
 -m <p>%         All matches with more than <p>% similarity will be saved.
 -r <dir>        (Result) Name of directory in which the web pages will be
                 stored (default: result)
 -bc <dir>       Name of the directory which contains the basecode (common framework)
 -c [files]      Compare a list of files.
 -l <language>   (Language) Supported Languages:
                 java19 (default), java 17, java15, java15dm, java12, java11, python3, c/c++, c#-1.2, char, text, scheme

Note: java19 refers to all java version from 9 on (currently 9 - 12).


Assume that we want to check students' solutions that are written in Java 11.

Each student solution is in its own directory, say student1, student2, and so on. All solutions are in a common directory, say exercise1.

To run JPlag, simply type java -jar jplag-yourVersion.jar -l java19 -r /tmp/jplag_results_exercise1/ -s /path/to/exercise1

Note: You have to specify the language exactly as they are printed by JPlag (running JPlag without command line arguments prints all available languages - and other options). E.g., if you want to process C++ files, you have specify -l c/c++ as language option.


-x <file> (eXclude) All files named in <file> will be ignored

The option -x requires an exclusion list saved as <file>. The exclusion list contains a number of suffixes. JPlag will ignore all files that end with one of the suffixes.

-c [files] (Compare) Compare a list of files

Example: java -jar jplag-yourVersion.jar -l java19 -c student1_file student2_file student3_file This option must be the last one. JPlag will compare just a list of files pairwise.

-bc <dir> (common framework) Name of the directory which contains the basecode

Example: java -jar jplag-yourVersion.jar -s -l java19 ./submissions -bc template This option includes files that were given out to students as a framework or to fill in blanks - the content is compared with each submission and matching parts are excluded from mutual student matching. <dir> is considered to be the name of a subdirectory, i.e. relative path from <root-dir>, residing somewhere in the submission directory, on the same level as student submissions. Note: Due to a bug in all versions you have to provide the base directory without a slash at the end (e.g template, not template/).

Building JPlag

To build and run a local installation of JPlag, you can use the pom.xml in this directory (aggregator). It builds JPlag and the available frontends.

To generate single modules run mvn clean generate-sources package in the base directory; if you want a single file then run mvn clean generate-sources assembly:assembly inside the jplag directory. You will find the JARs in the respective target directories. If you build a single JAR, it will be generated in jplag/target.

Web Service

Installing, running and maintaining a local web service is not recommended as the web service uses outdated libraries and (really) needs polishing.

If you want to do it anyway: atujplag is the client, webservice is the - yepp - web service.

Improving JPlag

We're happy to incorporate all improvements to JPlag into this code base. Feel free to fork the project and send pull requests.

Adding new languages

Adding a new language frontend is quite simple. Have a look at one of the jplag.frontend projects. All you need is a parser for the language (e.g., for ANTLR or for JavaCC) and a few lines of code that sends the tokens (that are generated by the parser) to JPlag.