android - 动态地在另一个 fragment 中添加一个 fragment

Question

我想在另一个 fragment 中动态添加一个 fragment 。外部 fragment 是一个 DialogFragment :

public class MapFragmentDialog extends DialogFragment implements OnMapClickListener, OnMapLongClickListener,
    OnMarkerDragListener {

FragmentManager fmanager;
Fragment fragment;
SupportMapFragment supportmapfragment;

public static MapFragmentDialog newInstance() {
    MapFragmentDialog f = new MapFragmentDialog();
    return f;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    super.onCreateView(inflater, container, savedInstanceState);

    View v = inflater.inflate(R.layout.map_fragment, container, false);

    // *********** add myMapFragment

    FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

    // add a fragment
    MyMapFragment myFragment = new MyMapFragment();
    fragmentTransaction.add(R.id.myfragment, myFragment);
    fragmentTransaction.commit();
    myMap = ((SupportMapFragment)getActivity().getSupportFragmentManager().findFragmentById(R.id.myMap)).getMap();

    return v;
}

ma​​p_fragment 布局是这样的:

<TextView
    android:id="@+id/txtHelp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:gravity="center_vertical"
    android:paddingBottom="6dip"
    android:textAlignment="center"
    android:textAppearance="?android:attr/textAppearanceSmall"
    android:textSize="12sp" />
<FrameLayout
    android:id="@+id/myfragment"
    android:layout_width="0px"
    android:layout_height="wrap_content" />

我的内部 fragment MyMapFragment:

public class MyMapFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View myFragmentView = inflater.inflate(R.layout.my_map_fragment, container, false);
    return myFragmentView;
}}

my_map_fragment 布局包含:

<fragment
    android:id="@+id/myMap"
    android:layout_width="match_parent"
    android:layout_height="300dp"
    class="com.google.android.gms.maps.SupportMapFragment" />

我在我的 DialogFragment 上获取 map fragment 时遇到异常，这一行出现 NullPointerException

myMap = ((SupportMapFragment)getActivity().getSupportFragmentManager().findFragmentById(R.id.myMap)).getMap();

Answer 1

我记得看到一些关于 fragment 中的 fragment 只能动态工作的东西，而不是通过将它们放置在 XML 中。我认为 Abd El-Rahman El-Tama 使用 frameLayout 而不是直接指定 fragment 的正确想法是正确的