Jface: Listviewer throws AssertionFailedException

Question

I want to create a Jface Listviewer, but it alway throw the following Exception:

 org.eclipse.core.runtime.AssertionFailedException: assertion failed: 
        at org.eclipse.core.runtime.Assert.isTrue(Assert.java:110)
        at org.eclipse.core.runtime.Assert.isTrue(Assert.java:96)
        at org.eclipse.jface.viewers.StructuredViewer.assertContentProviderType(StructuredViewer.java:1671)
        at org.eclipse.jface.viewers.StructuredViewer.setContentProvider(StructuredViewer.java:1661)
        at property.sheet.internalConstraint.ConstraintDialog.createDialogArea(ConstraintDialog.java:26)
        at org.eclipse.jface.dialogs.Dialog.createContents(Dialog.java:775)
        at org.eclipse.jface.window.Window.create(Window.java:432)
        at org.eclipse.jface.dialogs.Dialog.create(Dialog.java:1104)
        at org.eclipse.jface.window.Window.open(Window.java:791)
 ....

My createDialogArea method (where I create the ListViewer) looks like this:

protected Control createDialogArea(Composite parent) {
        Composite container = (Composite) super.createDialogArea(parent);
        lv = new ListViewer(container, SWT.SINGLE);
        lv.setContentProvider(new ConstraintDialogContentProvider());
        lv.setLabelProvider(new ConstraintDialogLabelProvider());
        lv.setInput(fm);
        return container;
    }

By debugging, it turned out that the exception is thrown after I set my contentProvider:

public class ConstraintDialogContentProvider implements IContentProvider {

    private List<Feature> features = new ArrayList<Feature>();

    @Override
    public void dispose() {
    }

    @Override
    public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
    }

    public Object[] getElements(Object input) {
        if (input instanceof FeatureMap) {
            FeatureMap fm = (FeatureMap) input;
            if (fm.getFeature() != null) {
                getAllFeatures(fm.getFeature());
                return features.toArray();
            } else {
                return null;
            }
        }
        return null;
    }

    private void getAllFeatures(Feature feature) {
        features.add(feature);
        .....
                // adds additional features
    }
}

I don't really understand what I'm doing wrong here. Any ideas?

Cheers, Phil

Answer 1

The content provider for ListViewer must implement IStructuredContentProvider not just IContentProvider . The assertContentProviderType call is checking this.