Mapfragment findFragmentById always null

问题:

I have problems to access the fragment of the map. getFragmentManager().findFragmentById(R.id.map)) returns always null. I don't know why. What's the problem?

Thank you!

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

        <TextView
            android:id="@+id/tvNombreCentro"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingBottom="10dp"
            android:text="Large Text"
            android:textAppearance="?android:attr/textAppearanceLarge" />


    <fragment
            android:id="@+id/map"
            android:name="com.google.android.gms.maps.SupportMapFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:tag="tag_fragment_map" />

    </LinearLayout>

And in the activity after the setContentView I try to access to the map, but I receive an exception

public class Mapa extends Activity {
private GoogleMap mMap;
private ActionBar ab;

private TextView tvNombreCentro;
private TextView tvTelefonoValor;
private TextView tvEMailValor;
private TextView tvWebValor;
private TextView tvDireccionValor;

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

    setContentView(R.layout.mapa_centro);
    GoogleMap mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
            .getMap();
}

回答1:

use this way:

SupportMapFragment mapFrag = (SupportMapFragment) getSupportFragmentManager()
                    .findFragmentById(R.id.map);

            map = mapFrag.getMap();

here is full code with sample:

回答2:

In case your problem is not solved, try this :

As you are using SupportMapFragment, while retrieving map, use

   GoogleMap mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

Also, change

   public class Mapa extends Activity {

to

   public class Mapa extends FragmentActivity {

回答3:

I had a similar problem when trying to get MapFragment but getting null because the device didn't have Google Play Services updated.

回答4:

Change in the layout

android:name = "com.google.android.gms.maps.SupportMapFragment"

by

android:name = "com.google.android.gms.maps.MapFragment".

Or, you can use getSupportFragmentManager() instead of getFragmentManager().