如何从firebase检索数据到谷歌地图？

Question

我正在尝试将经纬度数据从 firebase 检索到我的谷歌地图，但是当我运行应用程序时，标记不会显示。

这是我的代码：

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
    private FirebaseDatabase tracker;
    private DatabaseReference databaseLocation;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        tracker = FirebaseDatabase.getInstance();
        databaseLocation = tracker.getReference("lokasi3");

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

    @Override
    public void onMapReady(final GoogleMap googleMap) {
        databaseLocation.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for (DataSnapshot child : dataSnapshot.child("lokasi3").getChildren()) {
                    Lokasi3 lokasi3 = dataSnapshot.getValue(Lokasi3.class);
                    String latitude = child.child("latitude").getValue().toString();
                    String longitude = child.child("longitude").getValue().toString();
                    double loclatitude = Double.parseDouble(latitude);
                    double loclongitude = Double.parseDouble(longitude);
                    LatLng cod = new LatLng(loclatitude, loclongitude);
                    googleMap.addMarker(new MarkerOptions().position(cod).title(""));
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }
}

Answer 1

在 onCreate 中收听您的数据

 databaseLocation.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot child : dataSnapshot.child("lokasi3").getChildren()) {
            Lokasi3 lokasi3 = dataSnapshot.getValue(Lokasi3.class);
            String latitude = child.child("latitude").getValue().toString();
            String longitude = child.child("longitude").getValue().toString();
            double loclatitude = Double.parseDouble(latitude);
            double loclongitude = Double.parseDouble(longitude);
            LatLng cod = new LatLng(loclatitude, loclongitude);
            googleMap1.addMarker(new MarkerOptions().position(cod).title(""));
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }


});





GoogleMap googleMap1;//make it global

@Override
public void onMapReady(final GoogleMap googleMap) {
    googleMap1=googleMap;

}