private void updateNavItem() { service.getNavItems( null, new AsyncCallback<List<String>>() { @Override public void onFailure(Throwable caught) { System.out.println("Could not retrieve nav items"); } @Override public void onSuccess(List<String> result) { System.out.println("Received nav " + result.size() + " items"); Iterator<String> it = result.iterator(); navigation.clear(); while (it.hasNext()) { navigation.addItem(it.next()); } } }); }