public void onBookListChanged() {
mBarTabManager.switchTab(tab_collection);
CollectionFragment frag = (CollectionFragment) tab_collection.getFragment();
if (frag != null) frag.refreshBookList();
}
@Override
public void confirmDelete(int id) {
CollectionFragment frag = (CollectionFragment) tab_collection.getFragment();
if (frag != null) frag.deleteBook(id);
}