[教学] Android MapFragment.getMap()' on a null object reference

java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.GoogleMap com.google.android.gms.maps.MapFragment.getMap()' on a null object reference

ClassLoader.loadClass: The class loader returned by Thread.getContextClassLoader() may fail for processes that host multiple applications. You should explicitly specify a context class loader. For example: Thread.setContextClassLoader(getClass().getClassLoader());

Solution 解决方案

1. 
   
2. MapFragment mapFragment = (MapFragment) getChildFragmentManager().findFragmentById(R.id.mapView);
   
3. 
   
4. if(mapFragment == null){
   
5.     return;
   
6. }
   
7. 
   
8. googleMap = mapFragment.getMap();
   

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