Question

UPD：当我从数据库中获取时，我发现纬度和经度字段发生了一些不好的事情，例如它没有正确显示Toast。

我在我的项目中使用Firebase数据库。它会为Firebase数据库保存包含附加信息的位置，我需要在地图上显示与该位置对应的标记。

写作数据库工作没有完美。

然而，阅读根本不起作用。我已按照此guide将数据库定义为我的类中的字段，在onCreate方法中添加了实例化并添加了ValueListener。

 DatabaseReference databaseEvents;

 //some code

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
        databaseEvents = FirebaseDatabase.getInstance().getReference("events");
    }


 //somecode

 databaseEvents.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
          //  events.clear();
            Toast.makeText(MapsActivity.this, "LUL", Toast.LENGTH_SHORT).show();
            for (DataSnapshot event : dataSnapshot.getChildren()) {
                Event e = event.getValue(Event.class);
                events.add(e);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });


    //here I'm trying to display the markers.

当我尝试输出events的大小时，它总是打印0，因此它不会在地图上打印任何标记。

完整的代码在这里：

    public class MapsActivity extends AppCompatActivity implements OnMapReadyCallback, View.OnClickListener, GoogleMap.OnInfoWindowClickListener {

    private static final int PLACE_PICKER_REQUEST = 1;
    private GoogleMap mMap;
    private Button addEventBtn;
    private PlacePicker.IntentBuilder builder;
    private Place place;
    private EditText editEventName;
    private Spinner typeOfEvent;
    private LatLng coordOfNewMarker;
    private String nameOfNewMarker;
    private String typeOfNewMarker;

    private ViewGroup infoWindow;
    private TextView infoTitle;
    private TextView infoSnippet;
    private Button infoButton1, infoButton2;
    private OnInfoWindowElemTouchListener infoButtonListener1, infoButtonListener2;

    DatabaseReference databaseEvents;

    @Override
    public void onClick(View v) {
        place = null;
        switch (v.getId()) {
            case R.id.AddEventButton:
                callPlacePicker();
                break;
        }
    }

    @Override
    public void onInfoWindowClick(Marker marker) {
        Toast.makeText(this, "Info window clicked",
                Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
        databaseEvents = FirebaseDatabase.getInstance().getReference("events");
    }

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

        addEventBtn = findViewById(R.id.AddEventButton);

        final MapWrapperLayout mapWrapperLayout = findViewById(R.id.map_relative_layout);
        mapWrapperLayout.init(mMap, getPixelsFromDp(MapsActivity.this, 39 + 20));

        // We want to reuse the info window for all the markers,
        // so let's create only one class member instance
        this.infoWindow = (ViewGroup)getLayoutInflater().inflate(R.layout.custom_infowindow, null);
        this.infoTitle = infoWindow.findViewById(R.id.nameTxt);
        this.infoSnippet = infoWindow.findViewById(R.id.addressTxt);
        this.infoButton1 = infoWindow.findViewById(R.id.btnOne);
        this.infoButton2 = infoWindow.findViewById(R.id.btnTwo);

        this.infoButtonListener1 = new OnInfoWindowElemTouchListener(infoButton1,
                getResources().getDrawable(R.drawable.round_but_green_sel),
                getResources().getDrawable(R.drawable.round_but_red_sel))
        {
            @Override
            protected void onClickConfirmed(View v, Marker marker) {
                Toast.makeText(MapsActivity.this, marker.getTitle() + "'s button clicked!", Toast.LENGTH_SHORT).show();
            }
        };
        this.infoButton1.setOnTouchListener(infoButtonListener1);

        this.infoButtonListener2 = new OnInfoWindowElemTouchListener(infoButton2,
                getResources().getDrawable(R.drawable.round_but_green_sel),
                getResources().getDrawable(R.drawable.round_but_red_sel))
        {
            @Override
            protected void onClickConfirmed(View v, Marker marker) {
                Toast.makeText(MapsActivity.this, marker.getSnippet() + "'s button clicked!", Toast.LENGTH_SHORT).show();
            }
        };
        this.infoButton2.setOnTouchListener(infoButtonListener2);


        mMap.setInfoWindowAdapter(new GoogleMap.InfoWindowAdapter() {
            @Override
            public View getInfoWindow(Marker marker) {
                return null;
            }

            @Override
            public View getInfoContents(Marker marker) {
                infoTitle.setText(marker.getTitle());
                infoSnippet.setText(marker.getSnippet());
                infoButtonListener1.setMarker(marker);
                infoButtonListener2.setMarker(marker);
                mapWrapperLayout.setMarkerWithInfoWindow(marker, infoWindow);
                return infoWindow;
            }
        });

        final ArrayList<Event> events = new ArrayList<>();

        databaseEvents.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
              //  events.clear();
                Toast.makeText(MapsActivity.this, "LUL", Toast.LENGTH_SHORT).show();
                for (DataSnapshot event : dataSnapshot.getChildren()) {
                    Event e = event.getValue(Event.class);
                    events.add(e);
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

      /*
        This code was being used for SQLite database which now is not being used at all.
        ArrayList<Double> lat = new ArrayList<>();
        ArrayList<Double> lng = new ArrayList<>();
        ArrayList<String> name = new ArrayList<>();
        ArrayList<String> type = new ArrayList<>();

        String query = "SELECT * FROM "+ "locations";
        Cursor cursor = locations.getWritableDatabase().rawQuery(query,null);

        while(cursor.moveToNext()){
            lat.add(cursor.getDouble(cursor.getColumnIndex("lat")));
            lng.add(cursor.getDouble(cursor.getColumnIndex("lng")));
            name.add(cursor.getString(cursor.getColumnIndex("name")));
            type.add(cursor.getString(cursor.getColumnIndex("type")));
        }*/


        // It always print 0.
        Toast.makeText(MapsActivity.this, ((Integer) events.size()).toString(), Toast.LENGTH_SHORT).show();


        int sz = events.size();
        for(int i = 0; i < sz; i++) {
            mMap.addMarker(new MarkerOptions().position(new LatLng(Double.parseDouble(events.get(i).getLatitude()), Double.parseDouble(events.get(i).getLongitude())))
                    .title(events.get(i).getName())
                    .snippet(events.get(i).getType()));
        }

        addEventBtn.setOnClickListener(this);
    }


    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == PLACE_PICKER_REQUEST) {
            if (resultCode == RESULT_OK) {
                place = PlacePicker.getPlace(this, data);
                openDialog();
            }
        }

    }

    public void openDialog() {
        android.support.v7.app.AlertDialog.Builder builder = new android.support.v7.app.AlertDialog.Builder(this);


        LayoutInflater inflater = this.getLayoutInflater();
        View view = inflater.inflate(R.layout.layout_dialog, null);
        editEventName = view.findViewById(R.id.editEventName);
        typeOfEvent = view.findViewById(R.id.spinnerEventType);
        final LocationsDB locations = new LocationsDB(this);
        final StatsDB stats = new StatsDB(this);
        try {
            final String selected = typeOfEvent.getSelectedItem().toString();
        }
        catch (Exception e) {
            Toast.makeText(this, "BAD", Toast.LENGTH_LONG);
        }
        builder.setView(view)
                .setTitle("Create Event")
                .setNegativeButton("cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {

                    }
                })
                .setPositiveButton("create", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        coordOfNewMarker = place.getLatLng();
                        nameOfNewMarker = editEventName.getText().toString();
                        typeOfNewMarker = typeOfEvent.getSelectedItem().toString();
                        ContentValues event = new ContentValues();
                        Geocoder geocoder;
                        List<Address> addresses = new ArrayList<>();
                        geocoder = new Geocoder(getApplication(), Locale.getDefault());

                        try {
                            addresses = geocoder.getFromLocation(coordOfNewMarker.latitude,
                                    coordOfNewMarker.longitude,
                                    1); // Here 1 represent max location result to returned, by documents it recommended 1 to 5
                        } catch (IOException e) {
                            e.printStackTrace();
                        }

                        String address = addresses.get(0).getAddressLine(0);
                        event.put("lat", coordOfNewMarker.latitude);
                        event.put("lng", coordOfNewMarker.longitude);
                        event.put("name", nameOfNewMarker);
                        event.put("type", typeOfNewMarker);
                        event.put("address", address);
                        locations.insert(event);
                        addEvent(coordOfNewMarker.longitude, coordOfNewMarker.latitude, typeOfNewMarker, nameOfNewMarker, address);
                        ContentValues created = new ContentValues();
                        created.put("type", "created");
                        created.put("number", stats.get() + 1);
                        stats.update(created);
                        mMap.addMarker(new MarkerOptions().position(place.getLatLng()).title(editEventName.getText().toString())
                                .snippet(typeOfEvent.getSelectedItem().toString()));
                    }
                });

        builder.show();

    }

    public void callPlacePicker() {
        builder = new PlacePicker.IntentBuilder();
        try {
            startActivityForResult(builder.build(this), PLACE_PICKER_REQUEST);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static int getPixelsFromDp(Context context, float dp) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int)(dp * scale + 0.5f);
    }

    private void addEvent(Double lng, Double ltd, String type, String name, String address) {
            String id = databaseEvents.push().getKey();
            Event e = new Event(id, lng.toString(), ltd.toString(), type, name, address);
            databaseEvents.child(id).setValue(e);
            Toast.makeText(this, "Event added!", Toast.LENGTH_LONG).show();
    }
}

阅读Firebase数据库Android时遇到麻烦

0 个答案: