Android Come mostrare il percorso tra i marcatori su googlemaps

Question

Sto creando un'app che mostrerà la posizione dell'utente e metterà un marcatore in quella posizione. Dopo che l'utente si sposta. Il marcatore verrebbe rimosso e verrà creato un nuovo marcatore. Adesso. Voglio che i marcatori sul punto A e sul punto B siano codificati nell'app e mostrino il percorso sulla mappa. Dovrà utilizzare la strada più vicina sulla mappa. Ho fatto qualche ricerca ma ho trovato solo il vecchio codice datato 5 anni fa. Qualcuno potrebbe essere così gentile da guidarmi in questo.

Il punto A e il punto B sono in metodo LocationChanged.

import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.SupportMapFragment; 

import com.google.android.gms.maps.model.BitmapDescriptorFactory; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.Marker; 
import com.google.android.gms.maps.model.MarkerOptions; 

import android.content.Context; 
import android.content.Intent; 
import android.location.Criteria; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.os.Bundle; 
import android.provider.Settings; 
import android.support.v4.app.FragmentActivity; 
import android.widget.Toast; 

public class MainActivity extends FragmentActivity implements LocationListener { 
    private GoogleMap map; 
    private LocationManager locationManager; 
    private String provider; 
    LatLng coordinate; 
    Marker startPerc; 

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


     LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE); 
     boolean enabledGPS = service 
       .isProviderEnabled(LocationManager.GPS_PROVIDER); 
     boolean enabledWiFi = service 
       .isProviderEnabled(LocationManager.NETWORK_PROVIDER); 

     // Check if enabled and if not send user to the GSP settings 
     // Better solution would be to display a dialog and suggesting to 
     // go to the settings 
     if (!enabledGPS) { 
      Toast.makeText(this, "GPS signal not found", Toast.LENGTH_LONG).show(); 
      Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS); 
      startActivity(intent); 
     } 
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
    // Define the criteria how to select the location provider -> use 
    // default 
    Criteria criteria = new Criteria(); 
    provider = locationManager.getBestProvider(criteria, false); 
    Location location = locationManager.getLastKnownLocation(provider); 

    // Initialize the location fields 
    if (location != null) { 
     Toast.makeText(this, "Selected Provider " + provider, 
       Toast.LENGTH_SHORT).show(); 
     onLocationChanged(location); 
    } else { 

     //do something 
    } 


} 

/* Request updates at startup */ 
@Override 
protected void onResume() { 
    super.onResume(); 
    locationManager.requestLocationUpdates(provider, 300, 1, this); 
} 

/* Remove the locationlistener updates when Activity is paused */ 
@Override 
protected void onPause() { 
    super.onPause(); 
    locationManager.removeUpdates(this); 
} 

@Override 
public void onLocationChanged(Location location) { 

    double lat = location.getLatitude(); 
    double lng = location.getLongitude(); 
    Toast.makeText(this, "Location " + lat+","+lng, 
      Toast.LENGTH_LONG).show(); 
    LatLng coordinate = new LatLng(lat, lng); 
    Toast.makeText(this, "Location " + coordinate.latitude+","+coordinate.longitude, 
      Toast.LENGTH_LONG).show(); 
    if(map!=null){ 
     map.clear(); 
    } 
    //map.clear(); 
    GoogleMap map; 
    if(startPerc!=null){ 
     startPerc.remove(); 
    } 
    map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap(); 
    startPerc = map.addMarker(new MarkerOptions() 
    .position(coordinate) 
     .title("Start") 
     .snippet("Your Position") 
     .icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher))); 
    map.moveCamera(CameraUpdateFactory.newLatLngZoom(coordinate, 20)); 



    map.addMarker(new MarkerOptions() 
        .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)) 
        .position(new LatLng(3.214732, 101.747047)) 
        .title("Point A") 
        .snippet("Bus Stop") 
        .flat(true)); 

    map.addMarker(new MarkerOptions() 
        .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)) 
        .position(new LatLng(3.214507, 101.749697)) 
        .title("Point B") 
        .snippet("Bus Stop") 
        .flat(true)); 



startPerc.setIcon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher)); 

} 


@ Override 
public void onProviderDisabled(String provider) { 
    Toast.makeText(this, "Enabled new provider " + provider, 
      Toast.LENGTH_SHORT).show(); 

} 


@Override 
public void onProviderEnabled(String provider) { 
    Toast.makeText(this, "Disabled provider " + provider, 
      Toast.LENGTH_SHORT).show(); 

} 


@Override 
public void onStatusChanged(String provider, int status, Bundle extras) { 
    // TODO Auto-generated method stub 

} 
void Delay(int Seconds){ 
    long Time = 0; 
    Time = System.currentTimeMillis(); 
    while(System.currentTimeMillis() < Time+(Seconds*1000)); 
} 
} 

Nuovo codice fornito da K Neeraj. Si blocca ancora tristemente per favore controlla.

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 

import org.json.JSONObject; 

import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.OnMapReadyCallback; 
import com.google.android.gms.maps.SupportMapFragment; 

import com.google.android.gms.maps.model.BitmapDescriptorFactory; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.Marker; 
import com.google.android.gms.maps.model.MarkerOptions; 
import com.google.android.gms.maps.model.PolylineOptions; 

import android.content.Context; 
import android.content.Intent; 
import android.graphics.Color; 
import android.location.Criteria; 
import android.location.Location; 
import android.location.LocationListener; 
import android.location.LocationManager; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.provider.Settings; 
import android.support.v4.app.FragmentActivity; 
import android.util.Log; 
import android.widget.Toast; 

public class MainActivity extends FragmentActivity implements LocationListener { 
    private GoogleMap map; 
    private LocationManager locationManager; 
    private String provider; 
    LatLng coordinate; 
    Marker startPerc; 

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



     LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE); 
     boolean enabledGPS = service 
       .isProviderEnabled(LocationManager.GPS_PROVIDER); 
     boolean enabledWiFi = service 
       .isProviderEnabled(LocationManager.NETWORK_PROVIDER); 

     // Check if enabled and if not send user to the GSP settings 
     // Better solution would be to display a dialog and suggesting to 
     // go to the settings 
     if (!enabledGPS) { 
      Toast.makeText(this, "GPS signal not found", Toast.LENGTH_LONG).show(); 
      Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS); 
      startActivity(intent); 
     } 

     locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
     // Define the criteria how to select the location provider -> use 
     // default 
     Criteria criteria = new Criteria(); 
     provider = locationManager.getBestProvider(criteria, false); 
     Location location = locationManager.getLastKnownLocation(provider); 



     // Initialize the location fields 
     if (location != null) { 
      Toast.makeText(this, "Selected Provider " + provider, 
        Toast.LENGTH_SHORT).show(); 
      onLocationChanged(location); 
     } else { 

     //do something 
    } 


} 


/* Request updates at startup */ 
@Override 
protected void onResume() { 
    super.onResume(); 
    locationManager.requestLocationUpdates(provider, 300, 1, this); 
} 

/* Remove the locationlistener updates when Activity is paused */ 
@Override 
protected void onPause() { 
    super.onPause(); 
    locationManager.removeUpdates(this); 
} 

@Override 
public void onLocationChanged(Location location) { 

    double lat = location.getLatitude(); 
    double lng = location.getLongitude(); 
    Toast.makeText(this, "Location " + lat+","+lng, 
      Toast.LENGTH_LONG).show(); 
    LatLng coordinate = new LatLng(lat, lng); 
    Toast.makeText(this, "Location " + coordinate.latitude+","+coordinate.longitude, 
      Toast.LENGTH_LONG).show(); 



    if(map!=null){ 
     map.clear(); 
    } 

    GoogleMap map; 
    if(startPerc!=null){ 
     startPerc.remove(); 
    } 
    map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap(); 
    startPerc = map.addMarker(new MarkerOptions() 
    .position(coordinate) 
     .title("Start") 
     .snippet("Your Position") 
     .icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher))); 
    map.moveCamera(CameraUpdateFactory.newLatLngZoom(coordinate, 12)); 




    startPerc.setIcon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher)); 

// Assign your origin and destination 
// These points are your markers coordinates 
LatLng origin = new LatLng(3.214732, 101.747047); 
LatLng dest = new LatLng(3.214507, 101.749697); 

// Getting URL to the Google Directions API 
String url = getDirectionsUrl(origin, dest); 

DownloadTask downloadTask = new DownloadTask(); 

// Start downloading json data from Google Directions API 
downloadTask.execute(url); 
} 


private String getDirectionsUrl(LatLng origin,LatLng dest){ 


    // Origin of route 
    String str_origin = "origin="+origin.latitude+","+origin.longitude; 

    // Destination of route 
    String str_dest = "destination="+dest.latitude+","+dest.longitude; 

    // Sensor enabled 
    String sensor = "sensor=false"; 

    // Building the parameters to the web service 
    String parameters = str_origin+"&"+str_dest+"&"+sensor; 

    // Output format 
    String output = "json"; 

    // Building the url to the web service 
    String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters; 

    return url; 
} 



/** A method to download json data from url */ 
    private String downloadUrl(String strUrl) throws IOException{ 
     String data = ""; 
     InputStream iStream = null; 
     HttpURLConnection urlConnection = null; 
     try{ 
      URL url = new URL(strUrl); 

     // Creating an http connection to communicate with url 
     urlConnection = (HttpURLConnection) url.openConnection(); 

     // Connecting to url 
     urlConnection.connect(); 

     // Reading data from url 
     iStream = urlConnection.getInputStream(); 

     BufferedReader br = new BufferedReader(new InputStreamReader(iStream)); 

     StringBuffer sb = new StringBuffer(); 

     String line = ""; 
     while((line = br.readLine()) != null){ 
      sb.append(line); 
     } 

     data = sb.toString(); 

     br.close(); 

    }catch(Exception e){ 
     Log.d("Exception while downloading url", e.toString()); 
    }finally{ 
     iStream.close(); 
     urlConnection.disconnect(); 
    } 
    return data; 
} 

// Fetches data from url passed 
private class DownloadTask extends AsyncTask<String, Void, String>{ 

    // Downloading data in non-ui thread 
    @Override 
    protected String doInBackground(String... url) { 

     // For storing data from web service 
     String data = ""; 

     try{ 
      // Fetching the data from web service 
      data = downloadUrl(url[0]); 
     }catch(Exception e){ 
      Log.d("Background Task",e.toString()); 
     } 
     return data; 
    } 

    // Executes in UI thread, after the execution of 
    // doInBackground() 
    @Override 
    protected void onPostExecute(String result) { 
     super.onPostExecute(result); 

     ParserTask parserTask = new ParserTask(); 

     // Invokes the thread for parsing the JSON data 
     parserTask.execute(result); 
    } 
} 

/** A class to parse the Google Places in JSON format */ 
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{ 

    // Parsing the data in non-ui thread 
    @Override 
    protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) { 

     JSONObject jObject; 
     List<List<HashMap<String, String>>> routes = null; 

     try{ 
      jObject = new JSONObject(jsonData[0]); 
      DirectionsJSONParser parser = new DirectionsJSONParser(); 

      // Starts parsing data 
      routes = parser.parse(jObject); 
     }catch(Exception e){ 
      e.printStackTrace(); 
     } 
     return routes; 
    } 

    // Executes in UI thread, after the parsing process 
    @Override 
    protected void onPostExecute(List<List<HashMap<String, String>>> result) { 
     ArrayList<LatLng> points = null; 
     PolylineOptions lineOptions = null; 
     MarkerOptions markerOptions = new MarkerOptions(); 

     // Traversing through all the routes 
     for(int i=0;i<result.size();i++){ 
      points = new ArrayList<LatLng>(); 
      lineOptions = new PolylineOptions(); 

      // Fetching i-th route 
      List<HashMap<String, String>> path = result.get(i); 

      // Fetching all the points in i-th route 
      for(int j=0;j<path.size();j++){ 
       HashMap<String,String> point = path.get(j); 

       double lat = Double.parseDouble(point.get("lat")); 
       double lng = Double.parseDouble(point.get("lng")); 
       LatLng position = new LatLng(lat, lng); 

       points.add(position); 
      } 

      // Adding all the points in the route to LineOptions 
      lineOptions.addAll(points); 
      lineOptions.width(2); 
      lineOptions.color(Color.RED); 
     } 

     // Drawing polyline in the Google Map for the i-th route 
     map.addPolyline(lineOptions); 
    } 
} 




@ Override 
public void onProviderDisabled(String provider) { 
    Toast.makeText(this, "Enabled new provider " + provider, 
      Toast.LENGTH_SHORT).show(); 

} 


@Override 
public void onProviderEnabled(String provider) { 
    Toast.makeText(this, "Disabled provider " + provider, 
      Toast.LENGTH_SHORT).show(); 

} 


@Override 
public void onStatusChanged(String provider, int status, Bundle extras) { 
    // TODO Auto-generated method stub 

} 
void Delay(int Seconds){ 
    long Time = 0; 
    Time = System.currentTimeMillis(); 
    while(System.currentTimeMillis() < Time+(Seconds*1000)); 
} 
} 

Poi ho creato un nuovo DirectionJSONParser.java

import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import com.google.android.gms.maps.model.LatLng; 

public class DirectionsJSONParser { 

    /** Receives a JSONObject and returns a list of lists containing latitude and longitude */ 
    public List<List<HashMap<String,String>>> parse(JSONObject jObject){ 

     List<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String,String>>>() ; 
     JSONArray jRoutes = null; 
     JSONArray jLegs = null; 
     JSONArray jSteps = null; 

     try { 

      jRoutes = jObject.getJSONArray("routes"); 

      /** Traversing all routes */ 
      for(int i=0;i<jRoutes.length();i++){ 
       jLegs = ((JSONObject)jRoutes.get(i)).getJSONArray("legs"); 
       List path = new ArrayList<HashMap<String, String>>(); 

       /** Traversing all legs */ 
       for(int j=0;j<jLegs.length();j++){ 
        jSteps = ((JSONObject)jLegs.get(j)).getJSONArray("steps"); 

        /** Traversing all steps */ 
        for(int k=0;k<jSteps.length();k++){ 
         String polyline = ""; 
         polyline = (String)((JSONObject)((JSONObject)jSteps.get(k)).get("polyline")).get("points"); 
         List<LatLng> list = decodePoly(polyline); 

        /** Traversing all points */ 
        for(int l=0;l<list.size();l++){ 
         HashMap<String, String> hm = new HashMap<String, String>(); 
         hm.put("lat", Double.toString(((LatLng)list.get(l)).latitude)); 
         hm.put("lng", Double.toString(((LatLng)list.get(l)).longitude)); 
         path.add(hm); 
        } 
       } 
      routes.add(path); 
     } 
    } 

} catch (JSONException e) { 
    e.printStackTrace(); 
}catch (Exception e){ 
} 

return routes; 
} 
/** 
* Method to decode polyline points 
* Courtesy : http://jeffreysambells.com/2010/05/27/decoding-polylines-from-google-maps-direction-api-with-java 
* */ 
private List<LatLng> decodePoly(String encoded) { 

    List<LatLng> poly = new ArrayList<LatLng>(); 
    int index = 0, len = encoded.length(); 
    int lat = 0, lng = 0; 

    while (index < len) { 
     int b, shift = 0, result = 0; 
     do { 
      b = encoded.charAt(index++) - 63; 
      result |= (b & 0x1f) << shift; 
      shift += 5; 
     } while (b >= 0x20); 
     int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1)); 
     lat += dlat; 

     shift = 0; 
     result = 0; 
     do { 
      b = encoded.charAt(index++) - 63; 
      result |= (b & 0x1f) << shift; 
      shift += 5; 
     } while (b >= 0x20); 
     int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1)); 
     lng += dlng; 

     LatLng p = new LatLng((((double) lat/1E5)), 
      (((double) lng/1E5))); 
     poly.add(p); 
    } 

    return poly; 
} 
} 

Answer 1

@Override 
public void onLocationChanged(Location location) { 
.... 
startPerc.setIcon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher)); 

// Assign your origin and destination 
// These points are your markers coordinates 
LatLng origin = new LatLng(3.214732, 101.747047); 
LatLng dest = new LatLng(3.214507, 101.749697); 

// Getting URL to the Google Directions API 
String url = getDirectionsUrl(origin, dest); 

DownloadTask downloadTask = new DownloadTask(); 

// Start downloading json data from Google Directions API 
downloadTask.execute(url); 
} 


private String getDirectionsUrl(LatLng origin,LatLng dest){ 


    // Origin of route 
    String str_origin = "origin="+origin.latitude+","+origin.longitude; 

    // Destination of route 
    String str_dest = "destination="+dest.latitude+","+dest.longitude; 

    // Sensor enabled 
    String sensor = "sensor=false"; 

    // Building the parameters to the web service 
    String parameters = str_origin+"&"+str_dest+"&"+sensor; 

    // Output format 
    String output = "json"; 

    // Building the url to the web service 
    String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters; 

    return url; 
} 



/** A method to download json data from url */ 
    private String downloadUrl(String strUrl) throws IOException{ 
     String data = ""; 
     InputStream iStream = null; 
     HttpURLConnection urlConnection = null; 
     try{ 
      URL url = new URL(strUrl); 

     // Creating an http connection to communicate with url 
     urlConnection = (HttpURLConnection) url.openConnection(); 

     // Connecting to url 
     urlConnection.connect(); 

     // Reading data from url 
     iStream = urlConnection.getInputStream(); 

     BufferedReader br = new BufferedReader(new InputStreamReader(iStream)); 

     StringBuffer sb = new StringBuffer(); 

     String line = ""; 
     while((line = br.readLine()) != null){ 
      sb.append(line); 
     } 

     data = sb.toString(); 

     br.close(); 

    }catch(Exception e){ 
     Log.d("Exception while downloading url", e.toString()); 
    }finally{ 
     iStream.close(); 
     urlConnection.disconnect(); 
    } 
    return data; 
} 

// Fetches data from url passed 
private class DownloadTask extends AsyncTask<String, Void, String>{ 

    // Downloading data in non-ui thread 
    @Override 
    protected String doInBackground(String... url) { 

     // For storing data from web service 
     String data = ""; 

     try{ 
      // Fetching the data from web service 
      data = downloadUrl(url[0]); 
     }catch(Exception e){ 
      Log.d("Background Task",e.toString()); 
     } 
     return data; 
    } 

    // Executes in UI thread, after the execution of 
    // doInBackground() 
    @Override 
    protected void onPostExecute(String result) { 
     super.onPostExecute(result); 

     ParserTask parserTask = new ParserTask(); 

     // Invokes the thread for parsing the JSON data 
     parserTask.execute(result); 
    } 
} 

/** A class to parse the Google Places in JSON format */ 
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{ 

    // Parsing the data in non-ui thread 
    @Override 
    protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) { 

     JSONObject jObject; 
     List<List<HashMap<String, String>>> routes = null; 

     try{ 
      jObject = new JSONObject(jsonData[0]); 
      DirectionsJSONParser parser = new DirectionsJSONParser(); 

      // Starts parsing data 
      routes = parser.parse(jObject); 
     }catch(Exception e){ 
      e.printStackTrace(); 
     } 
     return routes; 
    } 

    // Executes in UI thread, after the parsing process 
    @Override 
    protected void onPostExecute(List<List<HashMap<String, String>>> result) { 
     ArrayList<LatLng> points = null; 
     PolylineOptions lineOptions = null; 
     MarkerOptions markerOptions = new MarkerOptions(); 

     // Traversing through all the routes 
     for(int i=0;i<result.size();i++){ 
      points = new ArrayList<LatLng>(); 
      lineOptions = new PolylineOptions(); 

      // Fetching i-th route 
      List<HashMap<String, String>> path = result.get(i); 

      // Fetching all the points in i-th route 
      for(int j=0;j<path.size();j++){ 
       HashMap<String,String> point = path.get(j); 

       double lat = Double.parseDouble(point.get("lat")); 
       double lng = Double.parseDouble(point.get("lng")); 
       LatLng position = new LatLng(lat, lng); 

       points.add(position); 
      } 

      // Adding all the points in the route to LineOptions 
      lineOptions.addAll(points); 
      lineOptions.width(2); 
      lineOptions.color(Color.RED); 
     } 

     // Drawing polyline in the Google Map for the i-th route 
     map.addPolyline(lineOptions); 
    } 
} 

Dai un'occhiata a questo tutorial,

Drawing Driving Route Directions Between Two Locations Using Google Directions In Google Map Android Api v2

Essa mostra come disegnare Cartina stradale tra due punti.

Answer 2

Ecco il codice completo con piccole modifiche. È solo più carino.

import android.app.Activity; 
import android.os.AsyncTask; 
import android.util.Log; 

import com.eddress.R; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.PolylineOptions; 

import org.json.JSONObject; 

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 

public class GoogleMapsPath { 

    public GoogleMap map; 

    public GoogleMapsPath(Activity context, GoogleMap map, LatLng origin, LatLng dest){ 
     this.map = map; 

     String url = getDirectionsUrl(origin,dest); 
     FetchUrl FetchUrl = new FetchUrl(); 
     FetchUrl.execute(url); 

    } 

    // Fetches data from url passed 
    private class FetchUrl extends AsyncTask<String, Void, String> { 

     @Override 
     protected String doInBackground(String... url) { 

      // For storing data from web service 
      String data = ""; 

      try { 
       // Fetching the data from web service 
       data = downloadUrl(url[0]); 
       Log.d("Background Task data", data.toString()); 
      } catch (Exception e) { 
       Log.d("Background Task", e.toString()); 
      } 
      return data; 
     } 

     @Override 
     protected void onPostExecute(String result) { 
      super.onPostExecute(result); 

      ParserTask parserTask = new ParserTask(); 

      // Invokes the thread for parsing the JSON data 
      parserTask.execute(result); 

     } 
    } 


    private String downloadUrl(String strUrl) throws IOException { 
     String data = ""; 
     InputStream iStream = null; 
     HttpURLConnection urlConnection = null; 
     try { 
      URL url = new URL(strUrl); 

      // Creating an http connection to communicate with url 
      urlConnection = (HttpURLConnection) url.openConnection(); 

      // Connecting to url 
      urlConnection.connect(); 

      // Reading data from url 
      iStream = urlConnection.getInputStream(); 

      BufferedReader br = new BufferedReader(new InputStreamReader(iStream)); 

      StringBuffer sb = new StringBuffer(); 

      String line = ""; 
      while ((line = br.readLine()) != null) { 
       sb.append(line); 
      } 

      data = sb.toString(); 
      Log.d("downloadUrl", data.toString()); 
      br.close(); 

     } catch (Exception e) { 
      Log.d("Exception", e.toString()); 
     } finally { 
      iStream.close(); 
      urlConnection.disconnect(); 
     } 
     return data; 
    } 


    private String getDirectionsUrl(LatLng origin, LatLng dest) { 

     // Origin of route 
     String str_origin = "origin=" + origin.latitude + "," + origin.longitude; 

     // Destination of route 
     String str_dest = "destination=" + dest.latitude + "," + dest.longitude; 

     // Sensor enabled 
     String sensor = "sensor=false"; 

     // Building the parameters to the web service 
     String parameters = str_origin + "&" + str_dest + "&" + sensor; 

     // Output format 
     String output = "json"; 

     // Building the url to the web service 
     String url = "https://maps.googleapis.com/maps/api/directions/" + output + "?" + parameters; 

     return url; 
    } 


    private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String, String>>>> { 

     // Parsing the data in non-ui thread 
     @Override 
     protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) { 

      JSONObject jObject; 
      List<List<HashMap<String, String>>> routes = null; 

      try { 
       jObject = new JSONObject(jsonData[0]); 
       Log.d("ParserTask",jsonData[0].toString()); 
       DirectionsJSONParser parser = new DirectionsJSONParser(); 
       Log.d("ParserTask", parser.toString()); 

       // Starts parsing data 
       routes = parser.parse(jObject); 
       Log.d("ParserTask","Executing routes"); 
       Log.d("ParserTask",routes.toString()); 

      } catch (Exception e) { 
       Log.d("ParserTask",e.toString()); 
       e.printStackTrace(); 
      } 
      return routes; 
     } 

     // Executes in UI thread, after the parsing process 
     @Override 
     protected void onPostExecute(List<List<HashMap<String, String>>> result) { 
      ArrayList<LatLng> points; 
      PolylineOptions lineOptions = null; 

      // Traversing through all the routes 
      for (int i = 0; i < result.size(); i++) { 
       points = new ArrayList<>(); 
       lineOptions = new PolylineOptions(); 

       // Fetching i-th route 
       List<HashMap<String, String>> path = result.get(i); 

       // Fetching all the points in i-th route 
       for (int j = 0; j < path.size(); j++) { 
        HashMap<String, String> point = path.get(j); 

        double lat = Double.parseDouble(point.get("lat")); 
        double lng = Double.parseDouble(point.get("lng")); 
        LatLng position = new LatLng(lat, lng); 

        points.add(position); 
       } 

       // Adding all the points in the route to LineOptions 
       lineOptions.addAll(points); 
       lineOptions.width(8); 
       lineOptions.color(R.color.globalRedLight); 

       Log.d("onPostExecute","onPostExecute lineoptions decoded"); 

      } 

      // Drawing polyline in the Google Map for the i-th route 
      if(lineOptions != null) { 
       map.addPolyline(lineOptions); 
      } 
      else { 
       Log.d("onPostExecute","without Polylines drawn"); 
      } 
     } 
    } 
}