如何从 firebase 数据库为多个 Google 地图标记添加单独的名称和说明

Question

我已经能够使用存储在 Firebase 实时数据库中的坐标在我的 Google 地图上添加多个标记，但当前的问题是我无法检索标记正确。最后一个标记的名称将分配给从数据库中检索到的所有标记。

我想要的是每个标记都有一个单独的名称和（描述）分配给它。 分享了 output and firebase database as well.

的屏幕截图

public class HistoricalMapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private static final int REQUEST_LOCATION_PERMISSION = 1009;
    private GoogleMap mMap;
    private ActivityMapsBinding binding;

    //update--Taking multiple markers from Realtime Database
    private MarkerOptions options = new MarkerOptions();
    private ArrayList<LatLng> latlngs = new ArrayList<>();
    private ArrayList<String> Names = new ArrayList<>();
    String Lat ,Lon,Names1, Names2;
    double latitude , longitude;
    //update--Taking multiple markers from Realtime Database

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


        binding = ActivityMapsBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());

        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);




        //update--Taking multiple markers from Realtime Database
        FirebaseDatabase database = FirebaseDatabase.getInstance();
        DatabaseReference myRef = database.getReference("Positions");
        myRef.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                for (DataSnapshot chidSnap : dataSnapshot.getChildren()) {

                    Lat = String.valueOf(chidSnap.child("Latitude").getValue());
                    Lon = String.valueOf(chidSnap.child("Longitude").getValue());
                   // Names1 = String.valueOf(chidSnap.getKey());

                    //Getting Value of Name of the Place
                    Names1 = String.valueOf(chidSnap.child("Name").getValue());

                    latitude= Double.parseDouble(Lat);
                    longitude= Double.parseDouble(Lon);
                    Names2 = Names1;

                    latlngs.add(new LatLng(latitude, longitude));
                    Names.add(Names2);

                }
                if(mMap != null) {
                    for (LatLng point : latlngs) {
                        options.position(point);
                        options.title(Names2);
                        options.snippet("someDesc");
                        mMap.addMarker(options);
                    }
                }

            }
            @Override
            public void onCancelled(DatabaseError databaseError) {
            }
        });
        //update--Taking multiple markers from Realtime Database

        mapFragment.getMapAsync(this);
    }



    private void addMapMarkers(){

    }


    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        //update--Taking multiple markers from Realtime Database
        for (LatLng point : latlngs) {
            options.position(point);
            options.title(Names1);
            options.snippet("someDesc");
            googleMap.addMarker(options);
        }
        //update--Taking multiple markers from Realtime Database


        //Adding custom maps style over here
        //******** THIS PART OF CODE EXCLUSIVELY DESIGNED TO FETCH THE CUSTOM MAPS.JSON TEMPLATE**********
        enableMyLocation();

        try {
            // Customise the styling of the base map using a JSON object defined
            // in a raw resource file.
            boolean success = googleMap.setMapStyle(
                    MapStyleOptions.loadRawResourceStyle(
                            this, R.raw.mapstyle));
            if (!success) {
                Log.e("MapsActivity", "Style parsing failed.");
            }
        } catch (Resources. NotFoundException e) {
            Log.e("MapsActivity", "Can't find style. Error: ", e);
        }
        //******** MAP STYLING CODE ENDS OVER HERE **********



/*        // Add a marker in Sydney and move the camera
        LatLng sydney = new LatLng(-34, 151);
        LatLng islamabad = new LatLng(33.68, 73.04);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Islamabad"));
        //moving the camera position to Islamabad.
        mMap.moveCamera(CameraUpdateFactory.newLatLng(islamabad));*/


    }

    //Getting the Users current Location

    private void enableMyLocation() {
        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            mMap.setMyLocationEnabled(true);
        } else {
            ActivityCompat.requestPermissions(this, new String[]
                            {Manifest.permission.ACCESS_FINE_LOCATION},
                    REQUEST_LOCATION_PERMISSION);
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {
        // Check if location permissions are granted and if so enable the
        // location data layer.
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case REQUEST_LOCATION_PERMISSION:
                if (grantResults.length > 0
                        && grantResults[0]
                        == PackageManager.PERMISSION_GRANTED) {
                    enableMyLocation();
                    break;
                }
        }
    }
}

Answer 1

The name of the last marker gets assigned to all the markers that are retrieved from the database.

发生这种情况是因为您使用以下方法为所有标记设置了相同的名称：

options.title(Names2);

由于您是在循环中执行此操作，因此在循环结束时，Names2 将保留最后一个元素的值，因此会出现这种行为。要解决这个问题，您应该根据每个列表中的位置设置标题。这可以像这样简单地完成：

int position = 0; // Initialised the counter.
for (LatLng point : latlngs) {
    options.position(point);
    options.title(Names.get(position)); // Set the title according to the position.
    options.snippet("someDesc");
    mMap.addMarker(options);
    position++; // Increment the position
}