android – mapFragment.getMap()返回null

我正在尝试从SupportMapFragment获取地图,但它返回null.从我读到的这可能是因为片段尚未完全显示,因此没有地图存在？！我尝试使用executePendingTransactions()修复它,但到目前为止没有成功.

任何想法如何解决它？

这是代码

private GoogleMap map;
private SupportMapFragment mapFragment;
@Override
public void onCreate( Bundle savedInstanceState ) {

    //...
    super.onCreate( savedInstanceState ); 
    setContentView( R.layout.screen_mission2 );
    GoogleMapOptions mapOptions = new GoogleMapOptions();

    mapOptions.mapType(GoogleMap.MAP_TYPE_norMAL)
        .compassEnabled(true)
        .rotateGesturesEnabled(false)
        .tiltGesturesEnabled(false);

    android.support.v4.app.FragmentManager myFragmentManager = getSupportFragmentManager();
    android.support.v4.app.FragmentManager.enableDebugLogging(true);
    mapFragment = SupportMapFragment.newInstance(mapOptions);
    FragmentTransaction fragmentTransaction = myFragmentManager.beginTransaction();
    fragmentTransaction.add(R.id.mapFragment,mapFragment);
    fragmentTransaction.commit();
    myFragmentManager.executePendingTransactions();

    if(mapFragment == null) Base.log("mapFragment==null");
    if(map==null){
        map = mapFragment.getMap();
        Base.log("map should have been initialized");
        if(map==null) Base.log("map still null");
    }
}

和布局文件：

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

它返回以下日志

V/FragmentManager(24224): add: SupportMapFragment{4078c4b8 id=0x7f06003d}
V/FragmentManager(24224): Allocated fragment index SupportMapFragment{4078c4b8 #1 id=0x7f06003d}
V/FragmentManager(24224): moveto CREATED: SupportMapFragment{4078c4b8 #1 id=0x7f06003d}
D/EMR     (24224): map should have been initialized
D/EMR     (24224): map still null

解决方法

尝试将引用您的GoogleMap的所有代码移动到onStart()或onResume().直到片段经过onCreateView( link)之后才会实例化地图片段中的映射,这发生在父活动经过onCreate()之后.此外,无论如何,您都需要检查您的Google地图是否为空,因为如果未安装Google Play服务,或者地图由于某些其他原因而无法使用,则它将为null.