谷歌地图是空

Question

我可以建立谷歌地图的实例，并查看地图，但我不能的GetMap（），它总是空：

mMapFragment = SupportMapFragment.newInstance(); 
     FragmentTransaction fragmentTransaction = getSupportFragmentManager() 
       .beginTransaction(); 
     fragmentTransaction.replace(R.id.container, mMapFragment); 
     fragmentTransaction.commit(); 
     if (mMap == null) { 
      mMap = mMapFragment.getMap(); 
        // always null, why? 
      if (mMap != null) { 
       mMap.getUiSettings().setMyLocationButtonEnabled(true); 
      } 
     } 

Answer 1

This works pretty well for me ... 
It seems like it's the default background (which is black) of SurfaceView which is causing this bug . 

public class MyMapFragment extends SupportMapFragment() { 
@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    View view = super.onCreateView(inflater, container, savedInstanceState); 
    setMapTransparent((ViewGroup) view); 
    return view; 
}; 

private void setMapTransparent(ViewGroup group) { 
    int childCount = group.getChildCount(); 
    for (int i = 0; i < childCount; i++) { 
    View child = group.getChildAt(i); 
    if (child instanceof ViewGroup) { 
    setMapTransparent((ViewGroup) child); 
    } else if (child instanceof SurfaceView) { 
    child.setBackgroundColor(0x00000000); 
    } 
    } 
} 

}; 

Answer 2

地图将在编程创建时在onActivityCreated（）中可用。因此，尝试这样的：

mMapFragment = new SupportMapFragment() { 
     @Override 
     public void onActivityCreated(Bundle savedInstanceState) { 
      super.onActivityCreated(savedInstanceState); 

      if (mMap == null) { 
       mMap = this.getMap(); 

       //other code 
     } 
    }; 

入住这里：How do I know the map is ready to get used when using the SupportMapFragment?