问空对象引用android上的“'int java.util.List.size()”
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提问于 2018-07-24 07:31:22

回答 1查看 548关注 0票数 -2

我正在创建一个在地图上显示标记的应用程序。问题是，当我运行我的应用程序时，我得到了以下错误：

 java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
    at com.flag.app.app.fragment.FragmentMap$1.onMapReady(FragmentMap.java:186)
    at com.google.android.gms.maps.zzac.zza(Unknown Source)
    at com.google.android.gms.maps.internal.zzaq.onTransact(Unknown Source)
    at android.os.Binder.transact(Binder.java:380)

这是我的FragmentMap.class

公共类FragmentMap扩展了片段{

private GoogleMap googleMap;
public MapView mMapView;

 @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_map, container, false);

    mMapView =  rootView.findViewById(R.id.mapView);
    mMapView.onCreate(savedInstanceState);

    mMapView.onResume(); // needed to get the map to display immediately

    try {
        MapsInitializer.initialize(getActivity().getApplicationContext());
    } catch (Exception e) {
        e.printStackTrace();
    }

    mMapView.getMapAsync(new OnMapReadyCallback() {
        @RequiresApi(api = Build.VERSION_CODES.M)
        @Override
        public void onMapReady(GoogleMap mMap) {
            googleMap = mMap;
            Log.d("debug", "map ready called");
            LatLng lviv = new LatLng(49.838, 24.029);
            mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(lviv, 12));
            if (ActivityCompat.checkSelfPermission(getContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getContext(), android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                Log.d("debug", "problem");

            }

            List<Marker> markerList = getActivity().getIntent().getParcelableArrayListExtra(EXTRA_MARKER_LIST);
            for (int i = 0; i < markerList.size(); i++) {
                Marker marker = markerList.get(i);
                Location location = marker.getLocation();
                clusterManager.setItems(markerList);
            }
        }

    });

    return rootView;
}

这是我的数据库屏幕：