Créer un fragment sous Android

Bonjour
Voici le code Java qui permet de créer un fragment sous Android:
public class CardFlipActivity extends Activity {
...
/**
* A fragment representing the front of the card.
*/
public class CardFrontFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_card_front, container, false);
}
}

/**
* A fragment representing the back of the card.
*/
public class CardBackFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_card_back, container, false);
}
}
}