Pre-General Availability: 2017-05-24

jar

You can use the jar command to create an archive for classes and resources, and manipulate or restore individual classes or resources from an archive.

Synopsis

 jar [OPTION...] [ [--release VERSION] [-C dir] files] ...

Description

The jar command is a general-purpose archiving and compression tool, based on the ZIP and ZLIB compression formats. Initially, the jar command was designed to package Java applets or applications; however, beginning with JDK 9, users can use thejar command to create modular JARs. For transportation and deployment, it is usually more convenient to package modules as modular JARs.

The syntax for the jar command resembles the syntax for the tar command. It has several main operation modes, defined by one of the mandatory operation arguments. Other arguments are either options that modify the behavior of the operation or are required to perform the operation.

Note:

Although available and supported in JDK 9, the Applet API is marked as deprecated in preparation for removal in a future release. Instead of applets, consider alternatives such as Java Web Start or self-contained applications.

When modules or the components of an applet or application (files, images and sounds) are combined into a single archive, they can be downloaded by a Java agent (such as a browser) in a single HTTP transaction, rather than requiring a new connection for each piece. This dramatically improves download times. The jar command also compresses files, which further improves download time. The jar command also enables individual entries in a file to be signed so that their origin can be authenticated. A JAR file can be used as a class path entry, whether or not it is compressed.

An archive becomes a modular JAR when you include a module descriptor, module-info.class, in the root of the given directories or in the root of the .jar archive. The following operations described in Operation Modifiers Valid Only in Create and Update Modes are only valid when creating a modular jar or updating an existing non-modular jar:

  • --module-version

  • --hash-modules

  • --module-path

Note:

All mandatory or optional arguments for long options are also mandatory or optional for any corresponding short options.

Main Operation Modes

When using the jar command, you must specify the operation for it to perform. You specify the operation mode for the jar command by including the appropriate operation arguments described in this section. You can mix an operation argument with other one-letter options. Generally the operation argument is the first argument specified on the command line.

—c or --create

Creates the archive.

—i=FILE or --generate-index=FILE

Generates index information for the specified JAR archive.

—t or --list

Lists the table of contents for the archive.

—u or --update

Updates an existing JAR archive.

—x or --extract

Extracts the named (or all) files from the archive.

-d or --print-module-descriptor

Prints the module descriptor.

Operation Modifiers Valid in any Mode

You can use the following options to customize the actions of any operation mode included in the jar command.

-C DIR

Changes to the specified directory and includes the files specified at the end of the command line.

 jar [OPTION...] [ [--release VERSION] [-C dir] files]
-f=FILE or --file=FILE

Specifies the archive file name.

--release VERSION

Used to create a multi-release JAR file. Places all files specified at the end of the command line into a versioned directory of the JAR file (such as, META-INF/versions/VERSION/).

-v or --verbose

Sends or prints verbose output to standard output.

Operation Modifiers Valid Only in Create and Update Modes

You can use the following options to customize the actions of the create and the update main operation modes:

—e=CLASSNAME or --main-class=CLASSNAME

Specifies the application entry point for stand-alone applications bundled into a modular or executable modular JAR file.

-m=FILE or --manifest=FILE

Includes the manifest information from the given manifest file.

-M or --no-manifest

Doesn’t create a manifest file for the entries.

--module-version=VERSION

Specifies the module version, when creating a modular JAR file, or updating a non-modular JAR file.

--hash-modules=PATTERN

Computes and records the hashes of modules matched by the given pattern and that depend upon directly or indirectly on a modular JAR file being created or a non-modular JAR file being updated.

-p or --module-path

Specifies the location of module dependence for generating the hash.

@files

Reads jar options and filenames from a text file.

Operation Modifiers Valid Only in Create, Update, and Generate-index Modes

You can use the following options to customize the actions of the create (—c or --create) the update (—u or --update ) and the generate-index (—i or --generate-index=FILE ) main operation modes.

-0 or --no-compress

Stores without using ZIP compression.

Other Options

The following options are recognized by the jar command and not used with operation modes.

-h or --help[:compat]

Displays the command-line help for the jar command or optionally the compatibility help.

--help-extra

Displays help on extra options.

--version

Prints the program version.

Examples of jar Command Syntax

Example 1    Creates an archive, classes.jar, that contains two class files,Foo.class and Bar.class.
 jar --create --file classes.jar Foo.class Bar.class
Example 2   Creates an archive, classes.jar, by using an existing manifest,mymanifest, that contains all of the files in the directory foo/.
 jar --create --file classes.jar --manifest mymanifest -C foo/
Example 3   Creates a modular JAR archive,foo.jar , where the module descriptor is located in classes/module-info.class.
 jar --create --file foo.jar --main-class com.foo.Main --module-version 1.0 -C foo/classes resources
Example 4   Updates an existing non-modular JAR, foo.jar, to a modular JAR file.
 jar --update --file foo.jar --main-class com.foo.Main --module-version 1.0 -C foo/module-info.class
Example 5   Creates a versioned or multi-release JAR, foo.jar, that places files in the META-INF/versions/9 directory
 jar --create --file my.jar -C foo classes --release 9 -C foo9 classes
Example 6   Creates an archive, my.jar, by reading options and lists of class files from the file classes.list.

Note:

To shorten or simplify the jar command, you can specify arguments in a separate text file and pass it to the jar command with the at sign (@) as a prefix.

 jar --create --file my.jar @classes.list