Re: Beginner Problem - Manifest file

Knute Johnson <>
Mon, 30 May 2011 14:20:50 -0700
On 05/30/2011 01:53 PM, William Colls wrote:

Ubuntu 10.04.2 64 bit
Java 1.6.0_24
NetbeansIDE 6.8

I have built a small application containing two classes. When I build
the application in the IDE, it builds without error, and creates a .jar

When I try to run the .jar using the command

java -jar myapp.jar

I get the error

Failed to load Main-Class manifest attribute from myapp.jar

One of the class files does contain the main declaration

public static void main(String args)

 From my reading, I understand that there should be a file with the name
manifest.txt in the build directory that gets incorporated into the .jar
file, but I don't know what the contents of the file should be. My
original understanding of how the IDE worked led me to believe that it
would create the manifest file automatically, but this doesn't seem to
be happening.

Any guidance would be greatly appreciated.

Thanks for your time.

It can be any name, doesn't matter. The line you want is;

Main-Class: mypackage.MyClass

 From the docs on jar;

# attribute defined for stand-alone applications
# This attribute is used by stand-alone applications that are bundled
into executable jar files which can be invoked by the java runtime
directly by running "java -jar x.jar".

     * Main-Class :

       The value of this attribute defines the relative path of the main
application class which the launcher will load at startup time. The
value must not have the .class extension appended to the class name.


Knute Johnson

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