Unable to execute a function using reflection

Question

hi, i am developing a eclipse plugin . In this plugin i am using reflection to execute a function in a class present in another project which is a hibernate project.Whenever the invoke is used i.e mymethod.invoke(myobj);

it is giving this exception

java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
    at java.lang.reflect.Method.invoke(Method.java:599)
    at packagesearch.DummyExecution.execution(DummyExecution.java:154)
    at packagesearch.HelloWorldAction.run(HelloWorldAction.java:48)
    at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:251)
    at org.eclipse.ui.internal.WWinPluginAction.runWithEvent(WWinPluginAction.java:229)
    at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:583)
    at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:500)
    at org.eclipse.jface.action.ActionContributionItem$6.handleEvent(ActionContributionItem.java:452)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3823)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3422)
    at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2384)
    at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2348)
    at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2200)
    at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:495)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:490)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
    at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:193)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:386)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
    at java.lang.reflect.Method.invoke(Method.java:599)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1236)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1212)
Caused by: java.lang.NoClassDefFoundError: org.dom4j.DocumentException
    at java.lang.J9VMInternals.verifyImpl(Native Method)
    at java.lang.J9VMInternals.verify(J9VMInternals.java:72)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:134)
    at test.Example.demo1(Example.java:38)
    ... 36 more
Caused by: java.lang.ClassNotFoundException: org.dom4j.DocumentException
    at java.net.URLClassLoader.findClass(URLClassLoader.java:419)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:643)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:345)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:609)
    ... 40 more

what is the exact problem . i have used loader to load the class.Help

Answer 1

It means exactly what it says, it couldn't find the class org.dom4j.DocumentException. Most likely, your classpath is incorrect.

Answer 2

I wonder if this has anything to do with Hibernate using proxy objects to represent the persistent entities. So in essence, if you checked the class type for an entity x, you may get something like x_javassist_1334 because Hibernate wraps your object to add some persistence specific functionality. I would do a simple check and print out the classname for the object you're invoking the method on before proceeding any further.