半胱氨酸配方。总距离

Question

我在项目中使用半胱氨酸配方有问题。 它正在计算从起点到我当前点的距离。但是当我回到起点时，距离越来越小。 我如何获得总行程距离？如果我喜欢走圈子或者前进？

（编辑）

这是除XML之外的完整代码。 我有其他问题买我一步一步尝试。所以我不想问太多问题。 我的主要问题是这个公式是胡子配方。计算从当前点到起点的距离。 我需要实时旅行的总距离。

import java.io.IOException;
import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.content.Context;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends Activity {

    String addressString = "No address found";
    String latLongString = "Your Current Position is: ";

    double latitude = 10;
    double longitude = 10;
    double sLatitude;
    double sLongitude;
    double eLatitude;
    double eLongitude;
    double distance = 10;

    double el1 = 0;
    double el2 = 0;

    double counter = 2;

    TextView myLocationText;
    TextView myLatitude;
    TextView myLongitude;
    TextView myAddress;
    TextView startingLatitude;
    TextView startingLongitude;
    TextView endingLatitude;
    TextView endingLongitude;
    TextView myDistance;
    TextView myLogOut;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        LocationManager locationManager;
        String context = Context.LOCATION_SERVICE;
        locationManager = (LocationManager) getSystemService(context);

        Criteria criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE);
        criteria.setAltitudeRequired(false);
        criteria.setBearingRequired(false);
        criteria.setCostAllowed(true);
        criteria.setPowerRequirement(Criteria.POWER_LOW);

        String provider = locationManager.getBestProvider(criteria, true);
        Location location = locationManager.getLastKnownLocation(provider);

        myLatitude = (TextView) findViewById(R.id.Latitude);
        myLongitude = (TextView) findViewById(R.id.Longitude);
        myLocationText = (TextView) findViewById(R.id.myLocationText);
        myAddress = (TextView) findViewById(R.id.Address);
        startingLatitude = (TextView) findViewById(R.id.startingLatitude);
        startingLongitude = (TextView) findViewById(R.id.startingLongitude);
        endingLatitude = (TextView) findViewById(R.id.endingLatitude);
        endingLongitude = (TextView) findViewById(R.id.endingLongitude);
        myDistance = (TextView) findViewById(R.id.distance);
        myLogOut = (TextView) findViewById(R.id.logOut);

        if (location != null) {
            sLatitude = location.getLatitude();
            sLongitude = location.getLongitude();

        }

        updateWithNewLocation(location);

        locationManager.requestLocationUpdates(provider, 1000, 2,
                locationListener);

    }

    private final LocationListener locationListener = new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
            updateWithNewLocation(location);
        }

        @Override
        public void onProviderDisabled(String provider) {
            updateWithNewLocation(null);
        }

        @Override
        public void onProviderEnabled(String provider) {
        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
        }
    };

    private void updateWithNewLocation(Location location) {

        if (location != null) {
            latitude = location.getLatitude();
            longitude = location.getLongitude();

            eLatitude = location.getLatitude();
            eLongitude = location.getLongitude();
            distance = distance(sLatitude, eLatitude, sLongitude, eLongitude,
                    el1, el2);

            Geocoder gc = new Geocoder(this, Locale.getDefault());
            try {

                List<Address> addresses = gc.getFromLocation(latitude,
                        longitude, 1);
                StringBuilder sb = new StringBuilder();
                if (addresses.size() > 0) {
                    Address address = addresses.get(0);

                    for (int i = 0; i < address.getMaxAddressLineIndex(); i++)
                        sb.append(address.getAddressLine(i)).append("\n");
                    sb.append(address.getLocality()).append("\n");
                    sb.append(address.getPostalCode()).append("\n");
                    sb.append(address.getCountryName());
                }
                addressString = sb.toString();
            } catch (IOException e) {
            }
        } else {
            latLongString = "No location found";
        }

        myLocationText.setText(latLongString);
        myLatitude.setText("Latitude: " + latitude);
        myLongitude.setText("Longitude: " + longitude);
        myAddress.setText(addressString);
        startingLatitude.setText("Starting latitude: " + sLatitude);
        startingLongitude.setText("Starting longitude: " + sLongitude);
        endingLatitude.setText("Last latitude: " + eLatitude);
        endingLongitude.setText("Last longitude: " + eLongitude);
        myDistance.setText("Your distance to starting point: " + distance);

    }

    public static double distance(double lat1, double lat2, double lon1,
            double lon2, double el1, double el2) {

        final int R = 6371; // Radius of the earth

        double latDistance = Math.toRadians(lat2 - lat1);
        double lonDistance = Math.toRadians(lon2 - lon1);
        double a = Math.sin(latDistance / 2) * Math.sin(latDistance / 2)
                + Math.cos(Math.toRadians(lat1))
                * Math.cos(Math.toRadians(lat2)) * Math.sin(lonDistance / 2)
                * Math.sin(lonDistance / 2);
        double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
        double distance = R * c * 1000; // convert to meters

        double height = el1 - el2;

        distance = Math.pow(distance, 2) + Math.pow(height, 2);
        return Math.sqrt(distance);
    }

}