Re: Nine ways of identifying Class-Path in manifest that don't work

Lew <>
Wed, 23 Dec 2009 13:59:35 -0800 (PST)
Composer wrote:

I've read several posts about Class-Path and they generally seem to
assume that I know how to specify the location of a directory relative
to the directory of the jar being executed. I'm running OS X.

The jar to be executed is
   /Java projects/myname/utilities/DesktopApp.jar

The external jar containing classes I need is
   /Java projects/javamail/mail.jar

So the external jar file is two directories up and then one directory
down from my main jar.

The compiler is perfectly happy finding the classes in mail.jar.
If I explicitly load all the classes from mail.jar into
DesktopApp.jar, it executes fine.

Here are the variants I have tried in my manifest:

Class-Path: .;.../javamail/mail.jar
Class-Path: .;../javamail/mail.jar
Class-Path: .;./javamail/mail.jar
Class-Path: .:.../javamail/mail.jar
Class-Path: .:../javamail/mail.jar
Class-Path: .:./javamail/mail.jar
Class-Path: .../javamail/mail.jar
Class-Path: ../javamail/mail.jar
Class-Path: ./javamail/mail.jar

All nine of these attempts result in NoClassDefFoundError when I
execute DesktopApp.jar.

Am I being really stupid?

Your using it wrong. Relative paths in the manifest should never
involve going up, only across and down. You're supposed to copy the
necessary JARs into the installation directory of the application JAR,
or some descendant thereof.

The whole point of JARs is to provide a portable application delivery
vehicle. If you start depending on hard-coded absolute paths then you
have defeated the purpose.

Copy your JARs into the directory where the application JAR resides,
or some subdirectory thereof like "lib/" and the bluebirds of
happiness will sing.


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