无法从Firebase获取电话号码？

Question

我无法从Firebase数据库获取电话号码，即使我的参考表在给定表中也有电话号码，但仍然无法获取？我想在屏幕上显示

我尝试了我知道的所有可能的解决方案，进一步了解了。

private void loadAllAvailableDriver() {
    DatabaseReference driverLocation = FirebaseDatabase.getInstance().getReference(Common.driver_tbl);
    GeoFire gf = new GeoFire(driverLocation);
    GeoQuery geoQuery = gf.queryAtLocation(new GeoLocation(mLastLocation.getLatitude(),mLastLocation.getLongitude()),distance);
    geoQuery.removeAllListeners();
    geoQuery.addGeoQueryEventListener(new GeoQueryEventListener() {
        @Override
        public void onKeyEntered(String key, final GeoLocation location) {
            FirebaseDatabase.getInstance().getReference(Common.user_driver_tbl)
                    .child(key)
                    .addListenerForSingleValueEvent(new ValueEventListener() {
                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {
                            Rider rider = dataSnapshot.getValue(Rider.class);

                            //Add driver to map
                            mMap.addMarker(new MarkerOptions()
                                            .position(new LatLng(location.latitude,location.longitude))
                                            .flat(true)
                                            .title(rider.getPhone())
                                            .icon(BitmapDescriptorFactory.fromResource(R.drawable.car)));
                        }

.title(rider.getphone()) the error is in this line because it give null object reference error even I give the right reference there is phone number available