java - 如何在android中的fragment中使用谷歌地图？

Question

我试图在 fragment 中使用谷歌地图 api，但它总是返回 null。我无法处理它，任何帮助都会得到帮助。有代码；

public class Map extends android.app.Fragment implements OnMapReadyCallback {
    private MapView mMapView;
    private GoogleMap mGoogleMap;
    String response_vehicles;
    Location location;
    float map_zoom=14;
    public Map() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

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

        MapFragment mapFragment = (MapFragment) getFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        return mapView;
    }

    @Override
    public void onMapReady(GoogleMap map) {
        map.setMapType(GoogleMap.MAP_TYPE_HYBRID);
        if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        }
        LatLng sydney = new LatLng(-33.867, 151.206);

        map.setMyLocationEnabled(true);
        map.moveCamera(CameraUpdateFactory.newLatLngZoom(sydney, 13));

        map.addMarker(new MarkerOptions()
                .title("Sydney")
                .snippet("The most populous city in Australia.")
                .position(sydney));
    }
}

并且有xml文件；

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/map"
    tools:context=".Fragments.Map"
    android:name="com.google.android.gms.maps.SupportMapFragment" />

我在mapFragment.getMapAsync(this);处给出错误NullPointerException 我该如何解决这个问题？我认为 list 文件和权限是完全正确的。

Answer 1

这是在 fragment 类中使用 map 的解决方案

fragment 类

public class DemoMapFragment extends Fragment implements OnMapReadyCallback {
    private GoogleMap googleMap;
    private View rootView;

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        rootView = inflater.inflate(R.layout.activity_demo, container, false);
        // Try to obtain the map from the SupportMapFragment.
        SupportMapFragment mapFragment = SupportMapFragment.newInstance();
        getChildFragmentManager().beginTransaction().replace(R.id.map, mapFragment).commit();
        mapFragment.getMapAsync(this);

        return rootView;
    }


    @Override
    public void onMapReady(final GoogleMap googleMap) {
        this.googleMap = googleMap;

    }

}

还有你的 xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_demo"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>