Актуализации на местоположението на картата на Google и позициониране на маркер

Мога да добавя множество маркери в моята карта, но всеки път, когато отворя приложението отново, добавените маркери се изчистват и се показва само един маркер на текущото местоположение. Настоящият ми код е даден по-долу, какви промени трябва да направя, за да получавам постоянни актуализации на координатите на местоположението и да запазвам маркери, така че да присъстват всеки път, когато отворя картата си.

public class MainActivity extends FragmentActivity implements View.OnClickListener {

public static final String mapLongitude="longitude";
public static final String mapLatitude="latitude";
FragmentManager fm = getSupportFragmentManager();
Button displayareas;



private GoogleMap newmap; // Might be null if Google Play services APK is not available.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    displayareas = (Button) findViewById(R.id.display);
    displayareas.setOnClickListener(this);
    Log.d("Map","MapCreated");
    setUpMapIfNeeded();

}
@Override
public void onClick(View v) {
    if(v.getId()==R.id.display){
        Intent intent = new Intent(this, AllAreas.class);

        startActivity(intent);
    }

}

@Override
protected void onResume() {
    super.onResume();
    setUpMapIfNeeded();
}


private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the map.
    if (newmap == null) {
        // Try to obtain the map from the SupportMapFragment.
        newmap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();
        // Check if we were successful in obtaining the map.
        if (newmap != null) {
            setUpMap();
            Log.d("MAPS","Map working");


        }
        else Log.d("MAPS","not working");

    }
}


private void setUpMap() {

    newmap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker").snippet("Snippet"));

    // Enable MyLocation Layer of Google Map
    newmap.setMyLocationEnabled(true);

    // Get LocationManager object from System Service LOCATION_SERVICE
    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

    // Create a criteria object to retrieve provider
    Criteria criteria = new Criteria();

    // Get the name of the best provider
    String provider = locationManager.getBestProvider(criteria, true);

    // Get Current Location
    Location myLocation = locationManager.getLastKnownLocation(provider);

    // set map type
    newmap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

    // Get latitude of the current location
    double latitude = myLocation.getLatitude();

    // Get longitude of the current location
    double longitude = myLocation.getLongitude();

    // Create a LatLng object for the current location
    LatLng latLng = new LatLng(latitude, longitude);

    // Show the current location in Google Map
    newmap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

    // Zoom in the Google Map
    newmap.animateCamera(CameraUpdateFactory.zoomTo(20));
    newmap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("My location"));

    Log.d("LATITUDE",String.valueOf(latitude));
    Log.d("LONGITUDE",String.valueOf(longitude));
    GoogleMap.OnMarkerClickListener listener = new GoogleMap.OnMarkerClickListener() {

        @Override
        public boolean onMarkerClick(final Marker marker) {

            AddGeofenceFragment dFragment = new AddGeofenceFragment();
            // Show DialogFragment
            dFragment.show(fm, "Dialog Fragment");
            return true;
        }

    };

    newmap.setOnMarkerClickListener(listener);

    newmap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {

        @Override
        public void onMapClick(LatLng latLng) {

            // Creating a marker
            MarkerOptions markerOptions = new MarkerOptions();

            // Setting the position for the marker
            markerOptions.position(latLng);

            // Setting the title for the marker.
            // This will be displayed on taping the marker
            markerOptions.title(latLng.latitude + " : " + latLng.longitude);


            // Animating to the touched position
            newmap.animateCamera(CameraUpdateFactory.newLatLng(latLng));

            // Placing a marker on the touched position
            newmap.addMarker(markerOptions);
            Log.d("ADDED LATITUDE",String.valueOf(latLng.latitude));
            Log.d("ADDED LONGITUDE",String.valueOf(latLng.longitude));

            Toast.makeText(getApplicationContext(),"Block area updated",Toast.LENGTH_LONG).show();



        }
    });

}

}