Jarfix

If you double-click on a jar file, and your Java application does not start, your .jar association has been hijacked. You can fix the problem with Jarfix.

Jarfix is a lightweight, free Windows PC utility designed to address a common issue with Java-based applications on Windows. Often, system changes, new installations, or accidental misconfigurations cause .jar (Java ARchive) files to lose their file association with the Java Runtime Environment (JRE).

When this happens, attempting to open .jar files may prompt Windows to use an incorrect program or fail altogether. It resolves this by restoring the proper association, allowing Java applications to run smoothly without user intervention.

This tool is invaluable for developers, gamers, and anyone who regularly uses Java-based software on Windows.

The root cause of the problem above is, that a program has stolen the .jar association. If you have installed the Java Runtime Environment the first time, the file type called "jar" is assigned to javaw.exe correctly. "jar" is an abbreviation for "java archive" and javaw.exe is the correct program to execute a .jar. However, on Windows, any program can steal a file type at any time even if it is already associated with a Jarfix for PC.

Many zip/unzip programs prefer to do this because a jar is stored in the .zip format. If you double-click on a .jar, your pack program opens the file, rather than javaw runs the program, because your pack program ignores the meta-information which is also stored in a .jar. In the Oracle bug database there is the low-priority report 4912211 "add mechanism to restore hijacked .jar and .jnlp file extensions", but it has been closed as "Closed, Will Not Fix".

You may also miss the file connection with .jar if you are using a free OpenJDK without an installer. Reinstall the Java Runtime Environment or fix the Windows Registry manually each time this problem occurs.

You can fix this problem very easily with the small but reliable jarfix.exe program. Just double click on it to restore the .jar association with javaw.exe.

Key Features

Automatic Fix for .jar Associations
It scans for issues with .jar file associations and automatically repairs them, linking .jar files back to the installed JRE. This process is quick and doesn’t require manual configuration.

Lightweight and Fast
At under 1 MB, this program is minimalistic and efficient. It executes the fix almost instantaneously, using a tiny amount of system resources.

Broad Compatibility
It supports all recent versions of Windows and works with multiple Java versions, making it suitable for a wide range of setups.

Portable Application
The program doesn’t require installation. Users can run it directly from the download, making it easy to carry on a USB drive and use on multiple computers.

Open Source
The app is open-source software, meaning that users can inspect, modify, or enhance the code according to their requirements.

User Interface

It has an extremely simple user interface. In fact, it doesn’t have a visible GUI when run. Instead, it operates through a command prompt window that opens briefly to execute the fix and closes upon completion.

This minimalism is intentional, as Jarfix is designed for quick, straightforward repairs rather than extensive interaction. Users only need to run the program, and it takes care of everything automatically.

This simplicity makes this tool suitable even for novice users who may not have technical expertise.

Installation and Setup

Download: Visit the developer’s website or a reputable software repository like FileHorse.com to download the executable file.

Run: Double-click the downloaded file (jarfix.exe) to launch the application. A command prompt window will briefly appear, indicating that Jarfix is running.

Completion: The program will automatically close after the fix is applied. There’s no additional configuration required; the .jar association will be restored to the JRE.

How to Use

Double-click the jarfix.exe file: This will automatically open and close a command prompt window.

Verify: After running this software, try opening any .jar file. It should now open with the JRE or JDK as expected.

Re-run if Needed: Occasionally, other software installations may overwrite the file association again. Simply re-run Jarfix in these cases to restore functionality.

It doesn’t require any other interaction beyond running it. There are no settings or preferences to adjust, making it a hassle-free solution.

FAQ

What does Jarfix actually do?
It restores the file association for .jar files so that they open with the Java Runtime Environment (JRE). It’s particularly useful when .jar files stop working after installing other software.

Is Jarfix safe to use?
Yes, this program is a secure tool. It doesn’t contain malware or adware, and it only modifies file associations specifically for .jar files.

Can I use Jarfix on Mac or Linux?
No, the app is only available for Windows. Mac and Linux users typically don’t face this issue because these systems handle .jar associations differently.

Do I need to run Jarfix every time I restart my computer?
No, once Jarfix restores the .jar file association, it should remain fixed unless another program changes it. If that happens, simply re-run Jarfix.

Will Jarfix work with all versions of Java?
Yes, the tool is compatible with all Java versions installed on Windows. However, it’s essential to have a valid JRE installed on your system.

Alternatives

Manual Fixing via Windows Settings
Users can manually associate .jar files with the JRE by adjusting Windows file type associations. This process is more complex and requires users to navigate to the “Default Programs” settings in Windows.

Using Java Control Panel
Some users report success in restoring .jar functionality through the Java Control Panel. Under the “Advanced” tab, users can configure the runtime environment settings for Java applications.

Reinstalling Java
Reinstalling Java often resets file associations. This is a more time-consuming approach but ensures that all Java-related files are properly configured.

System Requirements

• Operating System: Windows 11, 10, 8 or 7 (compatible with all recent versions)
• Java Runtime Environment: A valid Java installation (JRE or JDK)
• Disk Space: Less than 1 MB

PROS

• Simple and automatic fix for .jar file association issues
• Lightweight, with no installation required
• Free and open-source
• Compatible with all versions of Java and recent Windows OS
• Portable and easy to use for all levels of users

CONS

• Only works on Windows systems
• Lack of official support and updates
• Limited to fixing .jar associations (no additional features)
• Lacks a GUI, which may confuse users expecting a standard application interface
• Occasionally needs re-running if file associations are overwritten
• Not useful if Java is not installed properly on the system