Question

I have 2 TableViewer controls in a composite (Supposed they are : viewer1, viewer2). When initialize application, one “viewer1” is filled data from server while “viewer2” is set null.

viewer1.setInput(getData());
viewer2.setInput(null);

Now I want to change some object from viewer1 to viewer2 via a context menu, the first time add is successful, but the next time when I fill object to viewer2, I always get this exception:
java.lang.UnsupportedOperationException

This didn’t happen if viewer2 contain some objects in advance, it only happens when viewer2 is empty.
This is the way I add move some data from viewer1 to viewer2 :

//get selected objects in Viewer1
IStructuredSelection selection= (IStructuredSelection) viewer1.getSelection();
if(selection!=null){
            selectedList=(List<MyObject>)selection.toList();
            for(MyObject obj: selectedList){
                //do something here
            }
            //remove all
            ((List<MyObject>)viewer1().getInput()).removeAll(selectedList);
            viewer1.refresh();
        }
//viewer1 get above List
if((List<MyObject>)viewer2.getInput()==null)
 viewer2.setInput(selectedList);
else {
 ((List<MyObject>)viewer2.getInput()).addAll(selectedList);  //(Line Error)
}
viewer2.refresh;

It works well at the first time in the IF condition, but the next time when viewer2 contained some data, I always get exception at above error line.
@Krumelur , I added stacktrace that I got:

!ENTRY org.eclipse.ui 4 0 2011-12-27 16:26:50.660
!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.UnsupportedOperationException
    at java.util.AbstractList.add(Unknown Source)
    at java.util.AbstractList.add(Unknown Source)
    at java.util.AbstractCollection.addAll(Unknown Source)
    at com.saltlux.om.client.customwidgets.NeutralSetWidget.getReviewFromOtherWidget(NeutralSetWidget.java:39)
    at com.saltlux.om.client.customwidgets.NeutralSetWidget$1.handleEvent(NeutralSetWidget.java:24)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1062)
    at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:774)
    at com.saltlux.om.client.customwidgets.PositiveSetWidget.add2TrainingSet(PositiveSetWidget.java:107)
    at com.saltlux.om.client.customwidgets.TrainingReviewWidget$10.run(TrainingReviewWidget.java:288)
    at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
    at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
    at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
    at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4165)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
    at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
    at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
    at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
    at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
    at com.saltlux.om.client.Application.start(Application.java:21)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    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:344)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1386)

Please help me out. Thanks so much for any answer!

Answer 1

Not all implementations of java.util.List interface support addAll() method. For example, the one that is returned by Arrays.asList() does not and this is the method used by StructuredSelection.toList().