Naver Map Multiple Markers (100+)

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <fragment android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/map"
        android:name="com.naver.maps.map.MapFragment" />

</androidx.constraintlayout.widget.ConstraintLayout>

package com.learn.navercloudapis;

import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.UiThread;
import androidx.fragment.app.FragmentActivity;
import androidx.fragment.app.FragmentManager;

import com.naver.maps.geometry.LatLng;
import com.naver.maps.map.CameraPosition;
import com.naver.maps.map.CameraUpdate;
import com.naver.maps.map.MapFragment;
import com.naver.maps.map.NaverMap;
import com.naver.maps.map.OnMapReadyCallback;
import com.naver.maps.map.overlay.Marker;

import java.util.Vector;

public class MainActivity extends FragmentActivity implements OnMapReadyCallback {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        FragmentManager fm = getSupportFragmentManager();
        MapFragment mapFragment = (MapFragment)fm.findFragmentById(R.id.map);
        if (mapFragment == null) {
            mapFragment = MapFragment.newInstance();
            fm.beginTransaction().add(R.id.map, mapFragment).commit();
        }

        mapFragment.getMapAsync(this);
    }

    @UiThread
    @Override
    public void onMapReady(@NonNull final NaverMap naverMap) {
        // Set camera initial position
        LatLng initialPosition = new LatLng(37.506855, 127.066242);
        CameraUpdate cameraUpdate = CameraUpdate.scrollTo(initialPosition);
        naverMap.moveCamera(cameraUpdate);

        // Defining the markers' positions (approximately 10,000 in the east, west, north, south, and south directions at intervals of 1 km, total)
        markersPosition = new Vector<LatLng>();
        for (int x = 0; x < 100; ++x) {
            for (int y = 0; y < 100; ++y) {
                markersPosition.add(new LatLng(
                        initialPosition.latitude - (REFERANCE_LAT * x),
                        initialPosition.longitude + (REFERANCE_LNG * y)
                ));
                markersPosition.add(new LatLng(
                        initialPosition.latitude + (REFERANCE_LAT * x),
                        initialPosition.longitude - (REFERANCE_LNG * y)
                ));
                markersPosition.add(new LatLng(
                        initialPosition.latitude + (REFERANCE_LAT * x),
                        initialPosition.longitude + (REFERANCE_LNG * y)
                ));
                markersPosition.add(new LatLng(
                        initialPosition.latitude - (REFERANCE_LAT * x),
                        initialPosition.longitude - (REFERANCE_LNG * y)
                ));
            }
        }

        // Events called when the camera is moved
        naverMap.addOnCameraChangeListener(new NaverMap.OnCameraChangeListener() {
            @Override
            public void onCameraChange(int reason, boolean animated) {
                freeActiveMarkers();
                // Only those within the visible distance of the defined marker positions are created
                LatLng currentPosition = getCurrentPosition(naverMap);
                for (LatLng markerPosition: markersPosition) {
                    if (!withinSightMarker(currentPosition, markerPosition))
                        continue;
                    Marker marker = new Marker();
                    marker.setPosition(markerPosition);
                    marker.setMap(naverMap);
                    activeMarkers.add(marker);
                }
            }
        });
    }

    // Declare variables to store marker information
    private Vector<LatLng> markersPosition;
    private Vector<Marker> activeMarkers;

    // Where is the camera currently looking at?
    public LatLng getCurrentPosition(NaverMap naverMap) {
        CameraPosition cameraPosition = naverMap.getCameraPosition();
        return new LatLng(cameraPosition.target.latitude, cameraPosition.target.longitude);
    }

    // Ensure that the position of the selected marker is within the viewing distance (within a 3 km radius of the position the camera is looking at)
    public final static double REFERANCE_LAT = 1 / 109.958489129649955;
    public final static double REFERANCE_LNG = 1 / 88.74;
    public final static double REFERANCE_LAT_X3 = 3 / 109.958489129649955;
    public final static double REFERANCE_LNG_X3 = 3 / 88.74;
    public boolean withinSightMarker(LatLng currentPosition, LatLng markerPosition) {
        boolean withinSightMarkerLat = Math.abs(currentPosition.latitude - markerPosition.latitude) <= REFERANCE_LAT_X3;
        boolean withinSightMarkerLng = Math.abs(currentPosition.longitude - markerPosition.longitude) <= REFERANCE_LNG_X3;
        return withinSightMarkerLat && withinSightMarkerLng;
    }

    // Markers displayed on the map Delete from the map
    private void freeActiveMarkers() {
        if (activeMarkers == null) {
            activeMarkers = new Vector<Marker>();
            return;
        }
        for (Marker activeMarker: activeMarkers) {
            activeMarker.setMap(null);
        }
        activeMarkers = new Vector<Marker>();
    }

}