从 Firebase 数据库中返回纬度和经度坐标的所有值

Question

我有POJO类，我将Firebase数据库中的所有值分配给该类，以便我可以返回纬度和经度坐标的双重值。我检索这些值的方法只返回所有纬度和经度值的0.0。

我在下面添加了我的代码：

波乔类

public class LocationModel {
private String id;
private String address;
private String image;
private String lat;
private String lng;
private String desc;

public LocationModel() {
}
public LocationModel(String id, String address, String image, String lat, String lng, String desc) {
    this.id = id;
    this.address = address;
    this.image = image;
    this.lat = lat;
    this.lng = lng;
    this.desc = desc;
}
public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public String getAddress() {
    return address;
}
public void setAddress(String address) {
    this.address = address;
}

public String getImage() {
    return image;
}
public void setImage(String image) {
    this.image = image;
}

public String getLat() {
    return lat;
}
public double setLat(String lat) {
    this.lat = lat;
    return 0;
}
public String getLng() {
    return lng;
}
public double setLng(String lng) {
    this.lng = lng;
    return 0;
}

我的方法显示所有纬度和经度坐标并显示为标记簇。

private void displayLocations() {
    DatabaseReference mapsrefrence=FirebaseDatabase.getInstance().getReference().child("places");
    mapsrefrence.child("testlocation").addListenerForSingleValueEvent(
            new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    if(dataSnapshot.hasChildren()) {
                        @SuppressWarnings("unchecked")
                        LatLngBounds bounds;
                        LatLngBounds.Builder builder = new LatLngBounds.Builder();
                        for (DataSnapshot postSnapshot: dataSnapshot.getChildren()) {
                            // TODO: handle the post
                            LocationModel location = postSnapshot.getValue(LocationModel.class);
                            LocationModel availableLocation = new LocationModel();
                            double latitude = availableLocation.setLat(location.getLat());
                            double longitude = availableLocation.setLng(location.getLng());
                            Log.i(TAG, "lat"+latitude);
                            // Create LatLng for each locations
                            LatLng mLatlng = new LatLng(latitude, longitude);
                            // Make sure the map boundary contains the location
                            builder.include(mLatlng);
                            bounds = builder.build();
                            // Add a marker for each logged location
                            MarkerOptions mMarkerOption = new MarkerOptions()
                                    .position(mLatlng)
                                    .title("Clubs")
                                    .icon(BitmapDescriptorFactory.fromResource(R.drawable.icon_map));
                            Marker mMarker = mMap.addMarker(mMarkerOption);
                            markerList.add(mMarker);
                            // Zoom map to the boundary that contains every logged location
                            mMap.animateCamera(CameraUpdateFactory.newLatLngBounds(bounds,
                                    MAP_ZOOM_LEVEL));
                        }

                    }
                    }
                @Override
                public void onCancelled(DatabaseError databaseError) {
                    Log.w(TAG, "getUser:onCancelled", databaseError.toException());
                }
            });
}

Answer 1

本节看起来是错误的：

LocationModel location = postSnapshot.getValue(LocationModel.class);
LocationModel availableLocation = new LocationModel();
double latitude = availableLocation.setLat(location.getLat());
double longitude = availableLocation.setLng(location.getLng());
Log.i(TAG, "lat"+latitude);

您将latitude和longitude变量设置为 setLat() 和 setLng() 的返回值，并且这两种方法每次都返回 0。

您还将创建一个不必要的额外位置模型实例。

这是您真正想要的：

LocationModel location = postSnapshot.getValue(LocationModel.class);
double latitude = location.getLat();
double longitude = location.getLng();
Log.i(TAG, "lat"+latitude);