Question

I created my first Ant script and it’s working pretty well. It compiles all my java sources, creates a .jar file and runs the program without even any warning.

But when i try to run my .jar from command line i get NoClassDefFoundError exceptions.

So, how to translate this Ant snippet to work from command line?

<property name="main.class" value="de.bfs.radon.omsimulation.OMMainFrame"/>

<path id="classpath">
  <fileset dir="${lib.dir}" includes="**/*.jar"/>
</path>

<target name="run" depends="jar">
  <java fork="true" classname="${main.class}">
    <classpath>
      <path refid="classpath"/>
      <path location="${bin.dir}/omsimulation-${version}.jar"/>
    </classpath>
  </java>
</target>

This is the command line:

# java -classpath lib/ -jar bin/omsimulation-0.4.45-beta3.jar

Throws:

Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: com/toedter/calendar/JDateChooser
    at de.bfs.radon.omsimulation.OMMainFrame.(OMMainFrame.java:133)
    at de.bfs.radon.omsimulation.OMMainFrame$1.run(OMMainFrame.java:106)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)

Why does my .jar file not work with the defined classpath? Further down the Ant script:

<target name="jar" depends="manifest">
  <mkdir dir="${bin.dir}" />
  <jar jarfile="${bin.dir}/omsimulation-${version}.jar" manifest="${src.dir}/omsimulation.manifest" compress="no" basedir="${build.dir}" includes="de/**" />
</target>

<target name="manifest" depends="compile">
  <manifestclasspath property="manifest.cp" jarfile="${bin.dir}/omsimulation-${version}.jar">
    <classpath refid="classpath" />
  </manifestclasspath>
  <manifest file="${src.dir}/omsimulation.manifest">
    <attribute name="Built-By" value="${author}"/>
    <attribute name="Main-Class" value="${main.class}"/>
  </manifest>
</target>

Again, running the Ant script works fine. I even tried adding the said libraries to my .jar but that only blows up the file size, the problem still persists.

<jar jarfile="${bin.dir}/omsimulation-${version}.jar" manifest="${src.dir}/omsimulation.manifest" compress="no" basedir="${build.dir}"> <!-- includes="de/**" /-->
  <fileset dir="${lib.dir}">
    <include name="**/*.jar" />
  </fileset>
</jar>

Any ideas on this?

Thanks a lot,
donc_oe

SOLVED: Thanks to perception, the unix command line i was looking for is:

# java -cp lib/*:bin/myjarfile.jar my.package.MyMainClass

And for Windows (note the ; semicolon):

# javaw -cp lib/*;bin/myjarfile.jar my.package.MyMainClass

Answer 1

The relevant thing to note from your build script is this:

<path id="classpath">
  <fileset dir="${lib.dir}" includes="**/*.jar"/>
</path>

With that little snippet you have defined a path construct in Ant, which you then refer to in your run task:

<target name="run" depends="jar">
  <java fork="true" classname="${main.class}">
    <classpath>
      <path refid="classpath"/>
      <path location="${bin.dir}/omsimulation-${version}.jar"/>
    </classpath>
  </java>
</target>

This is in effect executing:

java -cp ${lib.dir}/*.jar:${bin.dir}/omsimulation-${version}.jar ${main.class}

Of course, it does so without the squigly lines and the path(s) fully substituted. The main point being that the command you are trying to run yourself is not equivalent at all. When attempting to invoke from the command line you will need to include in the classpath all the necessar JAR’s containing your code and all third party libraries. Assuming everything is still bundled in the Ant created folders, something like:

java -cp <full-path-to-lib>/* -jar <full-path-to-bin>/omsimulation-0.4.45-beta3.jar

Or:

java -cp <full-path-to-lib?/*:<full-path-to-bin>/omsimulation-0.4.45-beta3.jar <MainClass>