public class FormView extends ViewPart implements ISelectionListener {

 public void init(IViewSite site) throws PartInitException {
  super.init(site);
  getSelectionService().addSelectionListener(this);
 }

 public void dispose() {
  getSelectionService().removeSelectionListener(this);
  super.dispose();
 }

 private ISelectionService getSelectionService() {
  return getSite().getPage().getWorkbenchWindow().getSelectionService();
 }
  public void selectionChanged(IWorkbenchPart p, ISelection sel) {

....
  }
....

}