What does the following error means? How can I fix this issue?

[color=#00FF40]BUILD FAILED
java.lang.NoClassDefFoundError: org/dom4j/DocumentException
at org.hibernate.tool.hbm2ddl.SchemaExportTask.getConfiguration(SchemaExportTask.java:185)
at org.hibernate.tool.hbm2ddl.SchemaExportTask.execute(SchemaExportTask.java:146)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
at org.apache.tools.ant.Task.perform(Task.java:348)
at org.apache.tools.ant.Target.execute(Target.java:357)
at org.apache.tools.ant.Target.performTasks(Target.java:385)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1337)
at org.apache.tools.ant.Project.executeTarget(Project.java:1306)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
at org.apache.tools.ant.Project.executeTargets(Project.java:1189)
at org.apache.tools.ant.Main.runBuild(Main.java:758)
at org.apache.tools.ant.Main.startAnt(Main.java:217)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)[/color]

I'm afraid this is an easy one to diagnose. It's also easy to fix.



That class there? It can't be located at runtime. Do you have the dom4j.jar file on your classpath? I'm guessing you don't. Put that jar on your classpath.

I'd also guess you're missing some other jar files as well. Make sure you have them all there!