Corrupt jar file

I have created开发者_如何学C a jar file in windows 7 using eclipse. When I am trying to open the jar file it says invalid or corrupt jar file. Can anyone suggest me why the jar file is invalid?

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This will happen when you doubleclick a JAR file in Windows explorer, but the JAR is by itself actually not an executable JAR. A real executable JAR should have at least a class with a main() method and have it referenced in MANIFEST.MF.

In Eclispe, you need to export the project as Runnable JAR file instead of as JAR file to get a real executable JAR.

Or, if your JAR is solely a container of a bunch of closely related classes (a library), then you shouldn't doubleclick it, but open it using some ZIP tool. Windows explorer namely by default associates JAR files with java.exe, which won't work for those kind of libary JARs.

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This regularly occurs when you change the extension on the JAR for ZIP, extract the zip content and make some modifications on files such as changing the MANIFEST.MF file which is a very common case, many times Eclipse doesn't generate the MANIFEST file as we want, or maybe we would like to modify the CLASS-PATH or the MAIN-CLASS values of it.

The problem occurs when you zip back the folder.

A valid Runnable/Executable JAR has the next structure:

myJAR (Main-Directory)
    |-META-INF (Mandatory)
             |-MANIFEST.MF (Mandatory Main-class: com.MainClass)
    |-com 
         |-MainClass.class (must to implement the main method, mandatory)
    |-properties files (optional)
    |-etc (optional)

If your JAR complies with these rules it will work doesn't matter if you build it manually by using a ZIP tool and then you changed the extension back to .jar

Once you're done try execute it on the command line using:

java -jar myJAR.jar 

When you use a zip tool to unpack, change files and zip again, normally the JAR structure changes to this structure which is incorrect, since another directory level is added on the top of the file system making it a corrupted file as is shown below:

**myJAR (Main-Directory)
    |-myJAR (creates another directory making the file corrupted)**
          |-META-INF (Mandatory)
                   |-MANIFEST.MF (Mandatory Main-class: com.MainClass)
          |-com 
              |-MainClass.class (must to implement the main method, mandatory)
          |-properties files (optional)
          |-etc (optional)

:)

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Could be because of issue with MANIFEST.MF. Try starting main class with following command if you know the package where main class is located.

java -cp launcher/target/usergrid-launcher-1.0-SNAPSHOT.jar co.pseudononymous.Server

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The problem might be that there are more than 65536 files in your JAR: Why java complains about jar files with lots of entries? The fix is described in this question's answer.

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Also, make sure that the java version used at runtime is an equivalent or later version than the java used during compilation

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This is the common issue with "manifest" in the error? Yes it happens a lot, here's a link: http://dev-answers.blogspot.com/2006/07/invalid-or-corrupt-jarfile.html

Solution:

Using the ant task to create the manifest file on-the-fly gives you and entry like:

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.6.2
Created-By: 1.4.2_07-b05 (Sun Microsystems Inc.)
Main-Class: com.example.MyMainClass

Creating the manifest file myself, with the bare essentials fixes the issue:

Manifest-Version: 1.0
Main-Class: com.example.MyMainClass

With more investigation I'm sure I could have got the dynamic meta-file creation working with Ant as I know other people do - there must be some peculiarity in the combination of my ant version (1.6.2), java version (1.4.2_07) and perhaps the current phase of the moon.

Notes:

Parsing of the Meta-inf file has been an issue that has come-up, been fixed and then come-up again for sun. See: Bug Id: 4991229. If you can work out if this bug exists in the your (or my) version of the Java SE you have more patience that me.

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As I just came across this topic I wanted to share the reason and solution why I got the message "invalid or corrupt jarfile":

I had updated the version of the "maven-jar-plugin" in my pom.xml from 2.1 to 3.1.2. Everything still went fine and a jar file was built. But somehow it obviously wouldn't run anymore.

As soon as i set the "maven-jar-plugin" version back to 2.1 again, the problem was gone.

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It can be a typo int the MANIFEST.MF too, p.ex. Build-Date with two :

  Build-Date:: 2017-03-13 16:07:12

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Try use the command jar -xvf fileName.jar and then do export the content of the decompressed file into a new Java project into Eclipse.

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If the jar file has any extra bytes at the end, explorers like 7-Zip can open it, but it will be treated as corrupt. I use an online upload system that automatically adds a single extra LF character ('\n', 0x0a) to the end of every jar file. With such files, there are a variety solutions to run the file:

• Use prayagubd's approach and specify the .jar as the classpath and name of the main class at the command prompt
• Remove the extra byte at the end of the file (with a hex-editor or a command like head -c -1 myjar.jar), and then execute the jar by double-clicking or with java -jar myfile.jar as normal.
• Change the extension from .jar to .zip, extract the files, and recreate the .zip file, being sure that the META-INF folder is in the top-level.
• Changing the .jar extension to .zip, deleting an uneeded file from within the .jar, and change the extension back to .jar

All of these solutions require that the structure of the .zip and the META-INF file is essentially correct. They have only been tested with a single extra byte at the end of the zip "corrupting" it.

I got myself in a real mess by applying head -c -1 *.jar > tmp.jar twice. head inserted the ASCII text ==> myjar.jar <== at the start of the file, completely corrupting it.

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Maybe this was just a fluke but the one time I had this error, I simply had to kill all javaw.exe processes that were running in the background. The executable JAR worked after that.

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It can be something so silly as you are transferring the file via FTP to a target machine, you go and run the .JAR file but this was so big that it has not yet been finished transferred :) Yes it happened to me..