| ClassCastException when accessing with another plugin object [message #256204] |
Sun, 27 June 2004 23:38  |
Eclipse User |
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Originally posted by: gtoor.pervasive.com
We are developing a RCP based application using 3.0 RC2. It consists of two
plugins (a viewer and an editor). The editor plugin uses the
ObjectContribution extension point to add a menu item to the viewer popup
menu. The menu item is displayed fine when a TableElement object is
selected in the viewer. However, I get a ClassCastException in the
selectionChanged() method when the action is invoked (See code below). When
I use the debugger and inspect the selection.getFirstElement(), it seems I
have a valid TableElement object (the object contains the class elements and
has the name of the table I need to edit). So why am I getting a
ClassCastException when casting in my method.
The TableElement class is defined in the viewer plugin which I am building
into a .jar file for use with the editor. The .jar file is specified using
the "library name" tag in the editor plugin.xml. Could this be a deployment
issue?
Any help will be greatly appreciated.
Gagan.
public class EditTableAction implements IObjectActionDelegate {
/* (non-Javadoc)
* @see
org.eclipse.ui.IActionDelegate#run(org.eclipse.jface.action. IAction)
*/
public void run(IAction action) {
....
}
public void selectionChanged(IAction action, ISelection tableSelection)
{
com.pervasive.pem.TableElement element;
if (tableSelection instanceof IStructuredSelection) {
selection = (IStructuredSelection) tableSelection;
// if ( selection.getFirstElement() instanceof TableElement)
element = (com.pervasive.pem.TableElement)
selection.getFirstElement(); // exception thrown here
}
}
}
!ENTRY org.eclipse.ui 4 4 Jun 27, 2004 22:32:28.306
!MESSAGE Could not create action delegate for id:
com.pervasive.utilities.tableeditor.actions.EditTableAction
Could not create action delegate for id:
com.pervasive.utilities.tableeditor.actions.EditTableAction
Reason:
!ENTRY org.eclipse.ui 4 4 Jun 27, 2004 22:32:28.306
!MESSAGE Internal plug-in action delegate error on creation.
!STACK 0
java.lang.ClassCastException
at
com.pervasive.utilities.tableeditor.actions.EditTableAction. selectionChanged
(EditTableAction.java:102)
at
org.eclipse.ui.internal.PluginAction.refreshEnablement(Plugi nAction.java:230
)
at
org.eclipse.ui.internal.PluginAction.createDelegate(PluginAc tion.java:117)
at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginActi on.java:247)
at
org.eclipse.jface.action.ActionContributionItem.handleWidget Selection(Action
ContributionItem.java:915)
at
org.eclipse.jface.action.ActionContributionItem.access$2(Act ionContributionI
tem.java:866)
at
org.eclipse.jface.action.ActionContributionItem$7.handleEven t(ActionContribu
tionItem.java:785)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java :82)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:796)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.ja va:2716)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java :2382)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.jav a:1363)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1334)
at
org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Work bench.java:253)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.j ava:141)
at com.pervasive.utilities.pem.PemApplication.run(PemApplicatio n.java:27)
at
org.eclipse.core.internal.runtime.PlatformActivator$1.run(Pl atformActivator.
java:334)
at
org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseS tarter.java:273)
at
org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseS tarter.java:128)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAcce ssorImpl.java:39
)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMe thodAccessorImpl
..java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.eclipse.core.launcher.Main.basicRun(Main.java:185)
at org.eclipse.core.launcher.Main.run(Main.java:638)
at org.eclipse.core.launcher.Main.main(Main.java:622)
Internal plug-in action delegate error on creation.
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| Re: ClassCastException when accessing with another plugin object [message #256225 is a reply to message #256204] |
Mon, 28 June 2004 03:30  |
| Eclipse User |
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Originally posted by: newsserver_mails.bodden.de
Gagan Toor wrote:
> The TableElement class is defined in the viewer plugin which I am building
> into a .jar file for use with the editor. The .jar file is specified using
> the "library name" tag in the editor plugin.xml. Could this be a deployment
> issue?
Yes, it could indeed be. Note that each Plugin has its own classloader.
Also each class of a Java program is actually fully qualified by
<Classloader>+<PackageFragement>+<ClassName>. Usually the first bit is
the same for all classes in the application. Not so here, cause your one
plugin creates a class of type
<EditorPlugin>+com.pervasive.pem.TableElement and the other one expects
one of <ViewPlugin>+com.pervasive.pem.TableElement. I guess that could
be your problem.
A factory in one of the plugins could help solving that problem.
Eric
--
Eric Bodden, ICQ: 12656220, http://www.bodden.de, PGP: BB465582
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