Estou criando um aplicativo que mostra a localização do usuário e coloca um marcador nessa posição. Depois que o usuário se move. O marcador seria removido e um novo marcador seria criado. Agora. Quero que os marcadores no ponto A e no ponto B sejam codificados no aplicativo e mostrem a rota no mapa. Ele deve usar a estrada mais próxima no mapa. Eu fiz algumas pesquisas, mas só encontro código antigo com 5 anos atrás. Alguém poderia ter a gentileza de me guiar por isso.

O ponto A e o ponto B estão no método 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));
}
}

Novo código fornecido por K Neeraj. Ainda trava, infelizmente, verifique.

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));
}
}

Então eu criei um novo 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;
}
}