android method (distance between())

 enter code here

 package tryanabtry.opa;
 import java.util.List;
 import android.content.Context;


import android.graphics.drawable.Drawable;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.OverlayItem;


 public class tryanabtry extends MapActivity{
private MapView mapView;
private MapController mc;

GeoPoint p, p2, p3, p4;
List<Overlay> mapOverlays;
Drawable drawable, drawable2 , drawable3, drawable4;
HelloItemizedOverlay itemizedOverlay, itemizedOverlay2 , itemizedOverlay3,    itemizedOverlay4;

    /** Called when the activity is first created. */

     @Override

        public void onCreate(Bundle savedInstanceState)

         {
          try{
       super.onCreate(savedInstanceState);

       setContentView(R.layout.main);


       /* Use the LocationManager class to obtain GPS locations */

      LocationManager mlocManager =    (LocationManager)getSystemService(Context.LOCATION_SERVICE);

  LocationListener mlocListener = new MyLocationListener();

  mlocManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, mlocListener);
   mapView = (MapView) findViewById(R.id.mapView);

   // enable Street view by default
    mapView.setStreetView(true);


     mapView.setBuiltInZoomControls(true);

         mc = mapView.getController();

      mc.setZoom(12); 
         addOverLays();
           }
         catch(Exception e){
Log.d("eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",e.getMessage());
}
}
public void addOverLays(){
String [] coordinates = {"31.216487288475037","29.932637214660645" ,"30.084123015403748", "51.5002" , "-0.1262","31.337149143218994"};
double lat = 31.216487288475037;//lat2 = 51.5002,lat3=29.987091422080994;
double log = 29.932637214660645;// log2 = -0.1262,log3=31.43909454345703;

p = new GeoPoint((int) (lat * 1E6), (int) (log * 1E6));
// p2 = new GeoPoint( (int) (lat2 * 1e6), (int) (log2 * 1e6));
// p3=new GeoPoint( (int) (lat3 * 1e6), (int) (log3 * 1e6));
mapOverlays = mapView.getOverlays();
drawable = this.getResources().getDrawable(R.drawable.ballon);
//drawable2 = this.getResources().getDrawable(R.drawable.ballon);
// drawable3 = this.getResources().getDrawable(R.drawable.ballon);

itemizedOverlay = new HelloItemizedOverlay(drawable,this);
//  itemizedOverlay2 = new HelloI开发者_如何学PythontemizedOverlay(drawable2,this);        
//  itemizedOverlay3 = new HelloItemizedOverlay(drawable3,this);    
OverlayItem overlayitem = new OverlayItem(p, "Cairo", " over1");
//  OverlayItem over2 = new OverlayItem(p2, "ulm", "over2");
//OverlayItem over3 = new OverlayItem(p3, "offff", "over3");

itemizedOverlay.addOverlay(overlayitem);

mapOverlays.add(itemizedOverlay);

// itemizedOverlay2.addOverlay(over2);
// mapOverlays.add(itemizedOverlay2);

// itemizedOverlay3.addOverlay(over3);
//   mapOverlays.add(itemizedOverlay3);
mc.setZoom(17); 
// mc.animateTo(p);
}


/* Class My Location Listener */



public class MyLocationListener implements LocationListener

{

@Override

public void onLocationChanged(Location loc)

{





GeoPoint point = new GeoPoint(    (int) (loc.getLatitude() * 1E6), 
        (int) (loc.getLongitude() * 1E6));
//DoubletoString(loc.getLatitude());

//DoubletoString(loc.getLongitude());
///////////////////////////////////////////////////
loc.getAccuracy();
////////////////////////////////////////////////////////////
String Text = "My current location is: " +

"Latitud ="+ loc.getLatitude() +

"Longitud =" + loc.getLongitude();



Toast.makeText( getApplicationContext(),

Text,

Toast.LENGTH_SHORT).show();
mc.animateTo(point);
///////////////////////////////////////7ewar el remove 

///////////////if (point ==p){
///////////////mapView.getOverlays().remove(p);
////////////////// }

}

      private double distance(double lat1, double lon1, double lat2, double lon2, char  unit) {
   Location loc = null;
        GeoPoint point = new GeoPoint(    (int) (loc.getLatitude() * 1E6), 
        (int) (loc.getLongitude() * 1E6));
       lat1=loc.getLatitude();
       lon1=loc.getLongitude();
       lat2= 31.216487288475037;
       lon2=29.932637214660645;
   double theta = lon1 - lon2;
   double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2)) +       Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.cos(deg2rad(theta));
    dist = Math.acos(dist);
  dist = rad2deg(dist);
  dist = dist * 60 * 1.1515;
  if (unit == 'K') {
    dist = dist * 1.609344;
  } else if (unit == 'N') {
    dist = dist * 0.8684;
    }
  return (dist);
}

//:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
//::  This function converts decimal degrees to radians             :::
//:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
private double deg2rad(double deg) {
  return (deg * Math.PI / 180.0);
}

//:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
//::  This function converts radians to decimal degrees             :::
//:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
private double rad2deg(double rad) {
  return (rad / Math.PI * 180.0);
}

private void DoubletoString(double latitude) {
// TODO Auto-generated method stub

}


public void onProviderDisabled(String provider)

{

Toast.makeText( getApplicationContext(),

"Gps Disabled",

Toast.LENGTH_SHORT ).show();

}


public void onProviderEnabled(String provider)

{

Toast.makeText( getApplicationContext(),

"Gps Enabled",

Toast.LENGTH_SHORT).show();

}


public void onStatusChanged(String provider, int status, Bundle extras)

{


}

protected boolean isRouteDisplayed() {
return false;
}

}/* End of Class MyLocationListener */


@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}


}


/* End of UseGps Activity*/

so here the method distance must get the distance between my current location and other location i enter ?!! is it work or there is something i must add to this method