MapFragment - NullPointerException - Google Maps V2 - Android

Question

我正在使用以下代码获取NullPointerException:

private ProjectionProxy proxy = new ProjectionProxy();
private GoogleMap mMap = null;
private Context context = this;

@Override
protected void onCreate(Bundle load) { 
    super.onCreate(load);

    setContentView(R.layout.fragment_ride_tracking);

    //mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.myMapView)).getMap();

    mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

    int result = GooglePlayServicesUtil.isGooglePlayServicesAvailable(context);

    mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
    mMap.setMyLocationEnabled(true);

    //SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.myMapView);
    //mMap = mapFragment.getMap();

    Log.e("RideTracking", "Google Map VALUE:"+mMap);

    if (mMap != null) { 
        proxy.setProjection(mMap.getProjection());
    }

发生NullPointerException的行是这行代码:

mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

我没有将我的mMap变量初始化为null.这是我的问题？

Answer 1

MainActivity.xml:

<?xml version="1.0" encoding="utf-8"?>
<fragment
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/map"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:name="com.google.android.gms.maps.SupportMapFragment"/>

MainActivity.java:

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