How do I access markers when they are added on the map by the user?

Question

When a user clicks on a position on the map, a dialog alert box opens up and prompts the user to whether or not he or she wants to add a marker, if yes the marker is added. I am trying to write another method that if the user passes this marker, the marker changes color.

I am having trouble writing the marker checking part of this.

My code:

public void onMapClick(){
    map.setOnMapClickListener(new OnMapClickListener() {
        @Override
        public void onMapClick(LatLng latlng) {

            dialogBox(latlng);
        }
    });
}
private void dialogBox(final LatLng latlng) {
    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(MapActivity.this);

    alertDialogBuilder.setTitle("Add Marker");

    alertDialogBuilder
    .setMessage("Add marker?").setCancelable(false)
    .setPositiveButton("yes", new DialogInterface.OnClickListener() {

        @Override
        public void onClick(DialogInterface dialog, int which) {

            double dialogLat = latlng.latitude;
            double dialogLng = latlng.longitude;

            dialogMarker = map.addMarker(new MarkerOptions()
        .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN))
            .position(latlng).title("dialog maker"));

            //if location hit, places marker around that area
            hitLocation(dialogLat,dialogLng);

        }
    })
    .setNegativeButton("no", new DialogInterface.OnClickListener() {

        //cancels
        }
    }); // create alert dialog show it
}
public void hitLocation( final double dialogLat, final double dialogLng){
    LocationListener ll = new LocationListener() {

        @Override
        public void onLocationChanged(Location location) {
            // TODO Auto-generated method stub

            double lat = location.getLatitude();
            double lon = location.getLongitude();

            final LatLng currentLatLon = new LatLng(lat, lon);


            //tracks weather or not person hit the location
            if((lat > (dialogLat- 0.0001) && lat < (dialogLat+ 0.0001)) &&
            (lon > (dialogLon - 0.0001) && lon < (dialogLon + 0.0001))){
                dialogMarker = map.addMarker(new MarkerOptions().position(currentLatLon)
            }
        } // other location listener methods

It works up to where I pass hitLocation(doubleLat,doubleLng) inside the onClick method for the alert dialog. What I think should happen is that when I place a marker on the map, hitLocation should check whether or not I actaully hit the location that the user set.

Answer 1

It's really not clear how this all comes together (at least for me). For example, I don't see how hitLocation(double, double) is even called, but I do see a couple of issues.

First off. Is this a typo?

    if((lat > (dialogLat- 0.0001) && lat < (dialogLng+ 0.0001)) 

did you mean

    if((lat > (dialogLat- 0.0001) && lat < (dialogLat+ 0.0001)) 

dialog**Lat** vs dialog**Lng**

I think you would be better off checking if a coordinate is close by using something like this.

Math.abs(value1 - value2) < someTolerance

latitudes and longitudes are not always positive.