Google 地图 getTag() 始终为 null，即使 setTag() 不是

Question

我正在尝试在下面的 addMarkers 方法中通过 marker.setTag(Object object) 添加标签。我已经调试以确保标签中设置的值中没有 null。但是，当我尝试通过 getTag() 检索标签数据时，我得到了 null，我不知道为什么以及我出了什么问题。

private void addMarkers() {
        resetMap();
        CollectionReference restaurantCollection = FirebaseFirestore.getInstance().collection("Restaurant_Data");
        restaurantCollection.get().addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
            @Override
            public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                for (QueryDocumentSnapshot documentSnapshot : queryDocumentSnapshots) {
                    GeoPoint restaurantPoints = documentSnapshot.getGeoPoint("geoPoint");
                    String restaurantName = documentSnapshot.getString("restaurantName");
                    String snippet = documentSnapshot.getString("restaurantDescription");
                    double lat = restaurantPoints.getLatitude();
                    double lng = restaurantPoints.getLongitude();
                    LatLng latLng = new LatLng(lat, lng);

                    if (googleMap != null) {
                        MarkerOptions markerOptions = new MarkerOptions().position(latLng).title(restaurantName).icon(BitmapDescriptorFactory.defaultMarker(162)).snippet(snippet);
                        googleMap.addMarker(markerOptions);
                        Marker marker = googleMap.addMarker(markerOptions);
                        RestaurantMarker restaurantMarker = new RestaurantMarker(documentSnapshot.getId(), marker);
                        markerRestaurantIdArrayList.add(restaurantMarker);
                        marker.setTag(restaurantMarker);
                    }
                }
            }
        });
    }

这是我检索标签的方法。我知道标记不仅不为空，而且是正确的，因为我在地图上获得了正确的纬度/位置以及标题和 sn-p：

@Override
    public void onInfoWindowClick(final Marker marker) {
        final AlertDialog.Builder builder = new AlertDialog.Builder(mapviewContext);
        builder.setMessage(marker.getSnippet()).setCancelable(true).setPositiveButton("See Menu", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                RestaurantMarker restaurantMarker = (RestaurantMarker)marker.getTag();
                if (restaurantMarker != null && marker.getTag() instanceof RestaurantMarker) {
                    Log.d(TAG, "restaurant ID:"+ restaurantMarker.getRestaurantId());
                    bundle.putString("restaurantId", restaurantMarker.getRestaurantId());
                    bundle.putString("restaurantName", marker.getTitle());
                    bundle.putBoolean("direction", true);
                    restaurantMapListener.onRestaurantMap(bundle);
                } else {
                    Log.d(TAG, "restaurant marker is null");
                }
                dialogInterface.cancel();
            }
        }).setNegativeButton("Calculate Distance", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                resetSelectedMarker();
                selectedMarker = marker;
                calculateDirections(marker);
                dialogInterface.dismiss();
                markerRestaurantName = marker.getTitle();
            }
        });
        final AlertDialog alert = builder.create();
        alert.show();
    }

最后是 RestaurantMaker POJO。这里也没有问题，因为我在其他地方使用它并且没有任何问题：

public class RestaurantMarker {
    public String restaurantId;
    public Marker restaurantMarker;

    public RestaurantMarker(String restaurantId, Marker restaurantMarker) {
        this.restaurantId = restaurantId;
        this.restaurantMarker = restaurantMarker;
    }

    public String getRestaurantId() {
        return restaurantId;
    }

    public void setRestaurantId(String restaurantId) {
        this.restaurantId = restaurantId;
    }

    public Marker getRestaurantMarker() {
        return restaurantMarker;
    }

    public void setRestaurantMarker(Marker restaurantMarker) {
        this.restaurantMarker = restaurantMarker;
    }
}

Answer 1

来自您的代码addMarkers()：

...
MarkerOptions markerOptions = new MarkerOptions().position(latLng).title(restaurantName).icon(BitmapDescriptorFactory.defaultMarker(162)).snippet(snippet);
googleMap.addMarker(markerOptions);
Marker marker = googleMap.addMarker(markerOptions);
RestaurantMarker restaurantMarker = new RestaurantMarker(documentSnapshot.getId(), marker);
markerRestaurantIdArrayList.add(restaurantMarker);
marker.setTag(restaurantMarker);
...

您将标记添加到googleMap 两次（在同一LatLng 位置）：一次在googleMap.addMarker(markerOptions); 行，然后在Marker marker = googleMap.addMarker(markerOptions); 行，但仅为“第二次添加”标记设置标签。可能当您尝试通过getTag() 为单击的标记检索标记数据时，它会调用“首次添加”标记而没有设置标记（因为两个标记具有相同的LatLng 坐标）。因此，尝试从 addMarkers() 方法中删除 googleMap.addMarker(markerOptions); 行：

...
MarkerOptions markerOptions = new MarkerOptions().position(latLng).title(restaurantName).icon(BitmapDescriptorFactory.defaultMarker(162)).snippet(snippet);
//googleMap.addMarker(markerOptions);  <-- delete this line
Marker marker = googleMap.addMarker(markerOptions);
RestaurantMarker restaurantMarker = new RestaurantMarker(documentSnapshot.getId(), marker);
markerRestaurantIdArrayList.add(restaurantMarker);
marker.setTag(restaurantMarker);
...