android - 如何在 google maps android 上添加标记？

Question

我是 Android 编程的初学者。我已经看过类似的问题和答案，但我仍然不明白为什么这不起作用。当我在模拟器上尝试此操作并单击某个位置时，没有出现任何标记。这是我的代码:

编辑:当我现在点击以下代码时，我得到一个标记。当我第二次单击 map 时，它只会给我一个运行时异常(NullPointer 异常):

public class MapViewFragment extends Fragment {

    MapView mMapView;
    private GoogleMap googleMap;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_map_view, container, false);
        mMapView = (MapView) rootView.findViewById(R.id.mapView);
        mMapView.onCreate(savedInstanceState);
        mMapView.onResume();

        Context context = getActivity().getApplicationContext();

        final LocationsDB locationsDB = new LocationsDB(context);

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

        mMapView.getMapAsync(new OnMapReadyCallback() {
            @Override
            public void onMapReady(GoogleMap mMap) {
                googleMap = mMap;
                googleMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
                    public void onMapClick(LatLng point) {
                        // Drawing marker on the map
                        MarkerOptions markerOptions = new MarkerOptions();
                        markerOptions.position(point);
                        markerOptions.title(point.latitude + " : " + point.longitude);
                        googleMap.clear();
                        googleMap.animateCamera(CameraUpdateFactory.newLatLng(point));
                        googleMap.addMarker(markerOptions);
                        // Create location object
                        Location location = new Location(point.latitude, point.longitude);
                        // add location to SQLite database
                        locationsDB.insert(location);
                    }
                });
            }
        });
        return rootView;
    }
}

记录消息:

7-20 07:33:00.076 5359-5359/? W/RcsService: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.rcs.service.service.a.a()' on a null object reference
     at com.google.android.rcs.service.e.b(SourceFile:43)
     at com.google.android.rcs.service.service.JibeService.onDestroy(SourceFile:162)
     at android.app.ActivityThread.handleStopService(ActivityThread.java:3569)
     at android.app.ActivityThread.-wrap26(Unknown Source:0)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1703)
     at android.os.Handler.dispatchMessage(Handler.java:105)
     at android.os.Looper.loop(Looper.java:164)
     at android.app.ActivityThread.main(ActivityThread.java:6540)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)


07-20 07:33:00.079 5359-5359/? E/ActivityThread: Service com.google.android.rcs.service.service.JibeService has leaked IntentReceiver com.google.android.rcs.service.provisioning.RcsReconfigurationSmsReceiver@741339 that was originally registered here. Are you missing a call to unregisterReceiver()?
   android.app.IntentReceiverLeaked: Service com.google.android.rcs.service.service.JibeService has leaked IntentReceiver com.google.android.rcs.service.provisioning.RcsReconfigurationSmsReceiver@741339 that was originally registered here. Are you missing a call to unregisterReceiver()?
     at android.app.LoadedApk$ReceiverDispatcher.<init>(LoadedApk.java:1310)
     at android.app.LoadedApk.getReceiverDispatcher(LoadedApk.java:1091)
     at android.app.ContextImpl.registerReceiverInternal(ContextImpl.java:1397)
     at android.app.ContextImpl.registerReceiver(ContextImpl.java:1370)
     at android.app.ContextImpl.registerReceiver(ContextImpl.java:1358)
     at android.content.ContextWrapper.registerReceiver(ContextWrapper.java:603)
     at com.google.android.rcs.service.provisioning.RcsSmsReceiver.a(SourceFile:12)
     at com.google.android.rcs.service.h.g(SourceFile:230)
     at com.google.android.rcs.service.h.<init>(SourceFile:212)
     at com.google.android.rcs.service.service.a.<init>(SourceFile:13)
     at com.google.android.rcs.service.e.a(SourceFile:32)
     at com.google.android.rcs.service.service.JibeService.d(SourceFile:145)
     at com.google.android.rcs.service.service.JibeService.onCreate(SourceFile:91)
     at android.app.ActivityThread.handleCreateService(ActivityThread.java:3404)
     at android.app.ActivityThread.-wrap4(Unknown Source:0)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1683)
     at android.os.Handler.dispatchMessage(Handler.java:105)
     at android.os.Looper.loop(Looper.java:164)
     at android.app.ActivityThread.main(ActivityThread.java:6540)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Answer 1

在 Google map 示例中查看此处 https://developers.google.com/maps/documentation/android-api/marker

如果你想在点击时添加标记你也可以看这里: http://wptrafficanalyzer.in/blog/adding-marker-on-touched-location-of-google-maps-using-android-api-v2-with-supportmapfragment/

概念是像下面的代码那样做:

// Setting a click event handler for the map
    googleMap.setOnMapClickListener(new OnMapClickListener() {

        @Override
        public void onMapClick(LatLng latLng) {

            // Creating a marker
            MarkerOptions markerOptions = new MarkerOptions();

            // Setting the position for the marker
            markerOptions.position(latLng);

            // Setting the title for the marker.
            // This will be displayed on taping the marker
            markerOptions.title(latLng.latitude + " : " + latLng.longitude);

            // Clears the previously touched position
            googleMap.clear();

            // Animating to the touched position
            googleMap.animateCamera(CameraUpdateFactory.newLatLng(latLng));

            // Placing a marker on the touched position
            googleMap.addMarker(markerOptions);
        }
    });