I am trying to learn eclipse 4 application development, I add a part my application through the application model, but the part does’t show itself.

the part class:
import javax.inject.Inject;
import org.eclipse.e4.ui.di.Focus;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Label;
@SuppressWarnings("all")
public class ObjectEditor {
@Inject
public ObjectEditor(Composite parent) {
parent.setLayout(new FillLayout());
new Label(parent, SWT.NONE).setText("hello e4");
}
@Focus
public void onFocus() {
//TODO Your code here
}
}
what’s wrong ?
Edit———————————————————————
I have found that, the workbench.xmi in the runtime folder of my project is not updated after I changed application model(the Application.e4xmi file), what step did I missed ?
Maybe you forgot to add to add
-clearPersistedStateto the program arguments of your launch configuration?