Why has it failed to load main-class manifest attribute from a JAR file

Question

I have created a JAR file in this way jar cf jar-file input-files  Now  I m trying to run it  Running it does not work  jre command is not found    jre -cp app jar MainClass   This does not work either   java -jar main jar    Failed to load Main-Class manifest attribute from main jar    I also found out that     To run an application packaged as a   JAR file  version 1 2 -- requires   Main-Class manifest header    What is the  Main-Class manifest header   How do I create it and where do I put it

User · Answer

The easiest way to be sure that you have created the runnable JAR file correctly, with the appropriate manifest file, is to use Eclipse to build it for you. In your Eclipse project, you basically just select File/Export from the menu, and follow the prompts.

That way, you can be sure that your JAR file is correct and will know to look elsewhere if there is still an issue. The process is described in full in FAQ How do I create an executable JAR file for a stand-alone SWT program?.

User · Answer

If your class path is fully specified in manifest  maybe you need the last version of java runtime environment  My problem fixed when i reinstalled the jre 8

User · Answer

If you using eclipse  try below  1  Right click on the project -  select Export 2  Select Runnable Jar file in the select an export destination 3  Enter jar s name and Select  Package required        second radio button  -  Finish  Hope this helps

User · Answer

Try  java -cp   mail-1 4 1 jar JavaxMailHTML    no need to have manifest file

User · Answer

I got this error  and it was because I had the arguments in the wrong order   CORRECT  java maui main Examples tagging -jar maui-1 0 jar    WRONG  java -jar maui-1 0 jar maui main Examples tagging

User · Answer

I m not sure I believe your symptoms    If the jre command isn t found  then running jre -cp app jar should give the same error Just adding a JAR file to the classpath shouldn t give the error you re seeing   I d expect you to see this error if you run   java -jar app jar   The Main-Class header needs to be in the manifest for the JAR file - this is metadata about things like other required libraries  See the Sun documentation for how to create an appropriate manifest  Basically you need to create a text file which includes a line like this   Main-Class  MainClass   Then run  jar cfm app jar manifest txt   class

User · Answer

You can run with   java -cp   app jar package MainClass   It works for me if there is no manifest in the JAR file

User · Answer

I faced the same problem  This unix command is not able to find the main class  This is because the runtime and compile time JDK versions are different  Make the jar through eclipse after changing the java compiler version  The following link helped me   http   crunchify com exception-in-thread-main-java-lang-unsupportedclassversionerror-comcrunchifymain-unsupported-major-minor-version-51-0   Try running the jar created after this step and then execute it

User · Answer

set the classpath and compile     javac -classpath  C  Program Files Java jdk1 6 0 updateVersion tools jar  yourApp java  create manifest txt     Main-Class  yourApp newline  create yourApp jar      jar cvf0m yourApp jar manifest txt yourApp class  run yourApp jar     java -jar yourApp jar

User · Answer

I was getting the same error when i ran  jar cvfm test jar Test class Manifest txt  What resolved it was this  jar cvfm test jar Manifest txt Test class  My manifest has the entry point as given in oracle docs  make sure there is a new line character at the end of the file   Main-Class  Test

User · Answer

I discovered that I was also having this error in NetBeans   I hope the following is helpful    Make sure that when you go to Project Configuration you set the main class you intend for running  Do a Build or Clean Build Place the jar file where you wish and try  java -jar  YourProject jar  again at the command line    This was the problem I was getting because I had other  test  programs I was using in NetBeans and I had to make sure the Main Class under the Run portion of the Project configuration was set correctly   many blessings  John P

[java] Why has it failed to load main-class manifest attribute from a JAR file?

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