Что делать если jar файлы не открываются
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Что делать если jar файлы не открываются

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How to Open a JAR File on Windows

Occasionally, you find applications or games distributed as .jar files instead of the usual .exe file. You can’t just double-click on a JAR file to run the app. How, then, do you open a JAR file?

Java used to be a popular coding language to create freeware games and applications. Even now, many freeware apps are distributed as .jar files, which Windows does not natively support. This article will walk you through ways to open JAR files on your computer.

Table of Contents

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What Is a JAR File?

Internet browsers used Java to offer a dynamic browsing experience. Games and other interactive applets were coded using Java and could run on any platform.

But there was a small problem. It took multiple HTTP requests to download all the assets required for that applet to work, slowing down its load time. A better approach would be to package all the files into a single file that Java could access to run an application.

And that’s exactly what the JAR file is. Inspired by WinZip, JAR is a file archive used by Java to hold anything from multimedia files to code and is accessible to Java applets.

Install Java on Your PC

The most straightforward method to open a JAR file is to install the Java Runtime Environment (JRE) on your computer. Not only does this give you the ability to open .jar files, but it also makes your system capable of running Java apps.

  1. Download the latest JRE version, head to Oracle’s official download page.

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  1. Scroll down to find the right installation package for your operating system. There are both online and offline installers. The online setup will simply download the necessary files during the installation while the offline version downloads all necessary files first and then will start the installation.

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  1. Run the downloaded file to begin the installation of JRE on your computer. Accept the license agreement to get the setup underway. Usually, the installer will automatically remove older versions of JRE, though you can do that manually if needed.

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  1. A completed installation allows you to run any Java app on your PC, including JAR files.

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Note that this only allows your computer to open JAR files using the method mentioned below, but it doesn’t associate the .jar extension, which means that if you attempt to double-click a JAR file, Windows still wouldn’t know what to do with the file.

Check the following section to learn how to open a JAR file once JRE has been installed.

Open From Command Prompt

To be clear, this isn’t a different method at all. You still need to have Java installed on your computer to open JAR files from the command prompt, so that step comes first.

Once you’ve installed Java on your computer using the process in the last section, you can then use the command prompt to open JAR files.

  1. Open Command Prompt as an administrator. Type cmd in the search bar to locate the application.

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  1. Enter the command java -jar C:pathtofile.jar , where “pathtofile” is the path of the file in question. You can copy the file to the C drive itself to make it easier, allowing you to enter just the file name.

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  1. Upon execution of the command, Windows will use the JRE to interpret the JAR file. You should now see the Java application running.

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Unless the application you want is distributed as an executable Java file, you’ll need to execute all these steps each time you run a JAR file.

Extract as an Archive

JAR files are archived data with a fancy name. Sure they’re meant for Java applications, but a .jar file only compresses and archives them into a single package, thereby letting you extract JAR files using any leading file extraction tool like WinRAR or 7-Zip. This will let you see the contents of the package, though you’ll still need the JRE if you want to run the application itself.

  1. Download the 7-Zip installer to extract .jar files.

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  1. Run the downloaded .exe file to install 7-Zip on your computer.

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  1. Navigate to the directory containing the JAR file you wish to extract.
  1. Right-click on the file, select 7-Zip, and then select Extract All.

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  1. The JAR file will be extracted into the directory.

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What is the Best Method To Open a JAR File on Windows 10?

JAR files are usually Java applications packaged into a single file. To run them, you need to have the Java Runtime Environment installed on your PC. As JRE is free to download, this is the easiest way to get .jar files working on your Windows computer.

On the other hand, if you just want to look at the contents of the JAR archive but not actually run it, you can always use a file extraction tool. Apps like 7-Zip or WinRAR can easily extract the contents of a .jar file.

Levin Roy is a software engineer who loves writing about technology. Whether it is Windows tips-and-tricks or in-depth guides about application development, Levin uses his practical experience and technical skills to create articles that can help solve tricky problems. Read Levin’s Full Bio

The jar Command

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 (not supported since JDK 11) or applications; however, beginning with JDK 9, users can use the jar command to create modular JARs. For transportation and deployment, it’s 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.

When modules or the components of an 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’s 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 valid only when creating or updating 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 file. -t or —list Lists the table of contents for the archive. -u or —update Updates an existing JAR file. -x or —extract Extracts the named (or all) files from the archive. -d or —describe-module Prints the module descriptor or automatic module name.

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.

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

-f= FILE or —file= FILE Specifies the archive file name. —release VERSION

Creates a multirelease JAR file. Places all files specified after the option into a versioned directory of the JAR file named META-INF/versions/ VERSION / , where VERSION must be must be a positive integer whose value is 9 or greater.

At run time, where more than one version of a class exists in the JAR, the JDK will use the first one it finds, searching initially in the directory tree whose VERSION number matches the JDK’s major version number. It will then look in directories with successively lower VERSION numbers, and finally look in the root of the JAR.

-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 standalone 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 or updating 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. @ file Reads jar options and file names 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

  • Create an archive, classes.jar , that contains two class files, Foo.class and Bar.class .

jar —create —file classes.jar Foo.class Bar.class

jar —create —file classes.jar —manifest mymanifest -C foo/

jar —create —file foo.jar —main-class com.foo.Main —module-version 1.0 -C foo/classes resources

jar —update —file foo.jar —main-class com.foo.Main —module-version 1.0 -C foo/module-info.class

jar —create —file foo.jar —main-class com.foo.Hello -C classes . —release 10 -C classes-10 .

The JAR file foo.jar now contains:

% jar -tf foo.jar META-INF/ META-INF/MANIFEST.MF com/ com/foo/ com/foo/Hello.class com/foo/NameProvider.class META-INF/versions/10/com/ META-INF/versions/10/com/foo/ META-INF/versions/10/com/foo/NameProvider.class

As well as other information, the file META-INF/MANIFEST.MF , will contain the following lines to indicate that this is a multirelease JAR file with an entry point of com.foo.Hello .

. Main-Class: com.foo.Hello Multi-Release: true

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