Problem with Manifest classpath

[John Sutt]

Dear all,

I'm trying to create a test .jar file, which includes other jars, I 'm using log4j-1.2.14.jar as my first test,
but getting the manifest file right (or something else?...) is driving me a bit nuts.

Now I'm using Maven, because I hoped it would do some magic and teach me how to do it right, but I ran
into the same problem as when I tried to do what I want manually.

My jar has the following structure:

- lib
  - log4j-1.2.14.jar
- META-INF
  - MANIFEST.MF
- org
  - sutt
    - maventest
      - App.class

App.class is the trivial Maven Hello world example, and I added a simple log.debug call to it with log4j. Note that this application works perfectly fine without packaging it into a jar.
The MANIFEST.MF file inside the jar looks like this:

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven
Built-By: jsutt
Build-Jdk: 1.6.0_13
Package: org.sutt.maventest
Main-Class: org.sutt.maventest.App
Class-Path: lib/log4j-1.2.14.jar

Now, if a run "java -jar myJarFile.jar" I get the following error:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Category
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Category

Why can't it find the log4j jar file ??? When I removed the lib/ from Classs-path and copied the log4j jar file to its parent directory, it also did not work with the same error.

Thanks in advance,
John.

[Vijitha Kumara]

Your Class-Path entries would work if they reference the jar files outside your JAR. So this would not work. Check One-Jar for what you need.

Now I'm using Maven, because I hoped it would do some magic ....

Which kind of magic ?

[John Sutt]

Hi,

Thanks for pointing me to One-Jar. It looks nice, but I'd also like to know how to make this work without one-jar.
I understand now, that without special classloading code, I have to put the log4j outside of my own .jar file.

I've put log4j-1.2.14.jar and myJar.jar in the same directory. The MANIFEST file inside myJar.jar looks like this:

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.7.1
Created-By: 11.3-b02 (Sun Microsystems Inc.)
Built-By: jsutt
Main-Class: org.sutt.testapp.Main
Class-Path: log4j-1.2.14.jar

There is no log4j classes or jars inside myJar.jar.
Both of the following command lines produce the same error:

java -cp log4j-1.2.14.jar -jar myJar.jar
java -jar myJar.jar

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Log
er
        at org.sutt.testapp.Main.<clinit>(Main.java:18)
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Logger
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
        ... 1 more
Could not find the main class: org.sutt.testapp.Main. Program will exit.

About Maven, I just meant that I hoped it would create a working example for me, such that I could copy it and learn from it.

John.

[John Sutt]

Aha, I finally found out how to get it working.
I did not tell the whole story yet. In my Ant build file,
I'd put an "index=true" which also generated an index
file together with the manifest in the meta-inf directory.

And that was the culprit, ... for some reason.
When I removed the index, suddenly the log4j classes did get found.
I guess, in case of such an index file, the classloader does not look outside
of the .jar anymore, or something like that.

Glad I got it fixed, though, and thanks for your help.

John.