How To Use ClickListener for Starting Marker position in Android Studio?

Question

This application purposed to get the distance from 2 points of coordinate. The ways is just to click in the map of the position place that you want to count the distance. But there's problem in the point's start, where the application cannot changes the position place.

this is my code:

public class MapsActivity extends FragmentActivity {

// the Google Map object
private GoogleMap mMap;
//ArrayList markerPoints;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // we set the layout for the Activity
    setContentView(R.layout.activity_maps);

    // the geocoder is instantiated for the first time
    geocoder=new Geocoder(this);

    // if there isn't a map, it will be created
    setUpMapIfNeeded();
}


// LatLng objects store a pair of terrestrial coordinates (latitude and longitude)
private static LatLng STARTING_MARKER_POSITION =new LatLng(3.099465, 101.717111);

/* distanceFrom indicates the starting point to calculate the distance from.
   It's initialized with STARTING_MARKER_POSITION
*/

private LatLng distanceFrom= STARTING_MARKER_POSITION;

// line will be drawn at the click event
private Polyline line=null;

// A Geocoder can transform a pair of latitude/longitude into a street address and viceversa.
// We'll use it in the listener
private static Geocoder geocoder=null;


private GoogleMap.OnMapClickListener clickListener=new GoogleMap.OnMapClickListener() {
    @Override
    public void onMapClick(final LatLng pos) {

        // this method is called when the user taps the map

        // if a line already appears, it's removed
        if (line!=null)
            line.remove();

        // a new line is created
        line = mMap.addPolyline(new PolylineOptions()
                .add(distanceFrom, pos)
                .width(9) // width of the line
                .color(Color.BLUE)); // line color

        // call the converter object for geocoding invocation and distance calculation
        new AddressConverter().execute(distanceFrom, pos);

    }
};


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

    // the availability of the GoogleMap will be checked before the Activity starts interacting with the user
    setUpMapIfNeeded();
}

private void setUpMapIfNeeded() {

    // the map is created only it has not been initialized
    if (mMap == null) {

        // the map is located in the layout
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

        // if a map exists, we proceed with initialization
        if (mMap != null) {
            setUpMap();
        }
    }
}

// Now it's time to configure the map. We can add markers, shapes, event handlers and so on
private void setUpMap() {

    // the camera will be positioned according to the new coordinates
    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(STARTING_MARKER_POSITION, 14));




    // we choose the type of the map: Satellite in this case
    mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

    // markerOptions describes the marker we want to place
    MarkerOptions markerOptions=new MarkerOptions()
            .position(STARTING_MARKER_POSITION)
            .draggable(true);

    // the marker has to be draggable as we'll move it

    // the marker is rendered on the map
    mMap.addMarker(markerOptions);

    // we define the object to invoke when the marker is dragged
    mMap.setOnMarkerDragListener(new GoogleMap.OnMarkerDragListener()
    {
        @Override
        public void onMarkerDragStart(Marker arg0)
        {
            // this method is called when the drag starts
            // the operation we need is the cancellation of a preexisting line
            if (line!=null)
                line.remove();
        }
        @Override
        public void onMarkerDragEnd(final Marker pos)
        {
            // we get the final position of the marker
            distanceFrom=pos.getPosition();

        }

        @Override
        public void onMarkerDrag(Marker arg0)
        {
            // operations performed during the movement. Nothing to do
        }
    });

    // the callback to invoke is set
    mMap.setOnMapClickListener(clickListener);
}

// we want to know which address corresponds to this location
// we use AsyncTask to perform slower operations on a separate thread
private class AddressConverter extends AsyncTask<LatLng,Void,String>
{
    // The ProgressDialog window we'll show during the calculation
    private ProgressDialog progress=null;

    // this method is called before the background job starts. It works on the main thread
    @Override
    protected void onPreExecute() {

        // ProgressDialog is shown
        progress= ProgressDialog.show(MapsActivity.this,"Distance calculator","We are calcultating the distance...", true,false);
    }

    // this method works on a separate thread
    // it performs geocoding operations to retrieve the address of the points and calculates the distance in meters between them
    @Override
    protected String doInBackground(LatLng... params) {

        float[] distance=new float[1];
        try {
            // the Location class contains what we need to calculate distances

            Location.distanceBetween(params[0].latitude,params[0].longitude,params[1].latitude,params[1].longitude,distance);

            // geocoding operations
            List<Address> fromResult=geocoder.getFromLocation(params[0].latitude,params[0].longitude,1);
            List<Address> toResult=geocoder.getFromLocation(params[1].latitude,params[1].longitude,1);

            // the message informs the user about the distance from the marker to the point selected with the click
            // if we have got both the addresses, we use them to compose the message, otherwise we show only the distance
            if (fromResult.size()>0 && toResult.size()>0)
            {
              //  ((TextView) findViewById(R.id.tvDuration)).setText(route.duration.text);
                 return "The distance between " + getAddressDescription(fromResult.get(0)) + " and " + getAddressDescription(toResult.get(0)) + " is " + Math.round(distance[0]) + " meters";
            }
            else
                return "The distance is " + Math.round(distance[0]) + " meters";

        }
        catch (IOException e) {
            return "The distance is " + Math.round(distance[0]) + " meters";
        }
    }

    @Override
    protected void onPostExecute(String message)
    {
        if (progress!=null)
            progress.dismiss();

        // The builder of the window is instantiated
        AlertDialog.Builder builder=new AlertDialog.Builder(MapsActivity.this);
        builder.setTitle("Distance");
        builder.setMessage(message);

        // the Alert dialog appears
        builder.show();
    }



}

// this method only formats the message with addresses
private String getAddressDescription(Address a)
{
    String city=a.getLocality();
    String address=a.getAddressLine(0);

    return "'"+address+"' ("+city+")";

}}

Answer 1

Use distanceBetween() method, It will give you exact distance in meters.

Location.distanceBetween(double startLatitude, double startLongitude,
double endLatitude, double endLongitude, float[] results);