Some users have experienced problems with building the Example Workspace and get the following Exception:

java.util.zip.ZipException: error in opening zip file

(or similar).

The reason is that there are .class files in the classpath (i.e. not a directory nor a jar file). Since version 1.6 Ant tries to open these files and searches for Manifest entries. This fails with with a java.util.zip.ZipException

How to avoid:

This problem occurs only when using Java 5 in combination with Ant 1.6. Using Ant 1.5 or Java 1.4 will fix the problem. Another solution is to kick .class files from the classpath (see exclude tag).

  <target name="build.class" depends="build.init">
    <javac srcdir="${SRC}" destdir="${BUILD.CLASSES}"
           debug="on" optimize="off" deprecation="on"
    	   nowarn="true">
      <classpath>
      	<fileset dir="${LIB}"/>
      	<!--fileset dir="${GENFWLIB}"/-->
      	<fileset dir="${GENFWLIB}">
      	        <include name="**/*.jar"/>
      	      	<exclude name="*.class"/>
      	</fileset>
      </classpath>
    </javac>
  	<copy todir="${BUILD.CLASSES}">
  		<fileset dir="${SRC}" includes="**/*.xml"/>
  	</copy>
  </target> <!-- build.class -->

Thanks to Wolfgang Frank for this hint!