Driving route from my location to destination in Google Maps Android API V2

In this article, we will develop an Android application which demonstrates how to draw a driving route from my location ( current location ) to a destination location in Google Maps Android API V2.

On taping a location in the Google Maps, a driving route will be drawn from my current location to the taped location. The route direction is obtained from Google Directions API.

This application is developed in Eclipse (4.2.1) with ADT plugin (21.1.0) and Android SDK (21.1.0) and tested in a real device (Android 2.3.6  -  GingerBread ).

1. Create a new Android application project namely “LocationRouteMyLocationV2″

Figure 1 : Create new Android application Project

2. Configure the project

Figure 2 : Configure the application project

3. Design application launcher icon

Figure 3 : Design application launcher icon

4. Create a blank activity

Figure 4 : Create a blank activity

5. Enter MainActivity details

Figure 5 : Enter MainActivity details

6. Download and configure Google Play Services Library in Eclipse

Google Map for Android is now integrated with Google Play Services. So we need to set up Google Play Service Library for developing Google Map application in Android.

Please follow the given below link to setup Google Play Service library in Eclipse.

http://developer.android.com/google/play-services/setup.html

Note : Please ensure that, the latest version of Google Play Service Library is installed

7. Add Google Play Services Library to this project

Figure 6 : Link Google Play Services library to this project

8. Get the API key for Google Maps Android API V2

We need to get an API key from Google to use Google Maps in Android application.

Please follow the given below link to get the API key for Google Maps Android API v2.

https://developers.google.com/maps/documentation/android/start

9. Add Android Support library to this project

By default, Android support library (android-support-v4.jar ) is added to this project by Eclipse IDE to the directory libs. If it is not added, we can do it manually by doing the following steps :

• Open Project Explorer by Clicking “Window -> Show View -> Project Explorer”
• Right click this project
• Then from popup menu, Click “Android Tools -> Add Support Library “

10. Update the layout file res/layout/activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <fragment
        android:id="@+id/map"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</RelativeLayout>

11. Create a new class namely “DirectionsJSONParser” in the file src/in/wptrafficanalyzer/locationroutemylocationv2/DirectionsJSONParser.java

package in.wptrafficanalyzer.locationroutedirectionmapv2;

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 : 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;
    }
}

12. Update the class “MainActivity” in the file src/in/wptrafficanalyzer/locationroutemylocationv2/MainActivity.java

package in.wptrafficanalyzer.locationroutemylocationv2;

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 android.app.Dialog;
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.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.util.Log;
import android.view.Menu;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
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.MarkerOptions;
import com.google.android.gms.maps.model.PolylineOptions;

public class MainActivity extends FragmentActivity implements LocationListener {

    GoogleMap mGoogleMap;
    ArrayList<LatLng> mMarkerPoints;
    double mLatitude=0;
    double mLongitude=0;

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

        // Getting Google Play availability status
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getBaseContext());

        if(status!=ConnectionResult.SUCCESS){ // Google Play Services are not available

            int requestCode = 10;
            Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status, this, requestCode);
            dialog.show();

        }else { // Google Play Services are available

            // Initializing
            mMarkerPoints = new ArrayList<LatLng>();

            // Getting reference to SupportMapFragment of the activity_main
            SupportMapFragment fm = (SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map);

            // Getting Map for the SupportMapFragment
            mGoogleMap = fm.getMap();

            // Enable MyLocation Button in the Map
            mGoogleMap.setMyLocationEnabled(true);

            // Getting LocationManager object from System Service LOCATION_SERVICE
            LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

            // Creating a criteria object to retrieve provider
            Criteria criteria = new Criteria();

            // Getting the name of the best provider
            String provider = locationManager.getBestProvider(criteria, true);

            // Getting Current Location From GPS
            Location location = locationManager.getLastKnownLocation(provider);

            if(location!=null){
                onLocationChanged(location);
            }

            locationManager.requestLocationUpdates(provider, 20000, 0, this);

            // Setting onclick event listener for the map
            mGoogleMap.setOnMapClickListener(new OnMapClickListener() {

                @Override
                public void onMapClick(LatLng point) {

                    // Already map contain destination location
                    if(mMarkerPoints.size()>1){

                        FragmentManager fm = getSupportFragmentManager();
                        mMarkerPoints.clear();
                        mGoogleMap.clear();
                        LatLng startPoint = new LatLng(mLatitude, mLongitude);

                        // draw the marker at the current position
                        drawMarker(startPoint);
                    }

                    // draws the marker at the currently touched location
                    drawMarker(point);

                    // Checks, whether start and end locations are captured
                    if(mMarkerPoints.size() >= 2){
                        LatLng origin = mMarkerPoints.get(0);
                        LatLng dest = mMarkerPoints.get(1);

                        // 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;
    }

    /** A class to download data from Google Directions URL */
    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 Directions 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;

            // 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
            mGoogleMap.addPolyline(lineOptions);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    private void drawMarker(LatLng point){
        mMarkerPoints.add(point);

        // Creating MarkerOptions
        MarkerOptions options = new MarkerOptions();

        // Setting the position of the marker
        options.position(point);

        /**
        * For the start location, the color of marker is GREEN and
        * for the end location, the color of marker is RED.
        */
        if(mMarkerPoints.size()==1){
            options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
        }else if(mMarkerPoints.size()==2){
            options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
        }

        // Add new marker to the Google Map Android API V2
        mGoogleMap.addMarker(options);
    }

    @Override
    public void onLocationChanged(Location location) {
        // Draw the marker, if destination location is not set
        if(mMarkerPoints.size() < 2){

            mLatitude = location.getLatitude();
            mLongitude = location.getLongitude();
            LatLng point = new LatLng(mLatitude, mLongitude);

            mGoogleMap.moveCamera(CameraUpdateFactory.newLatLng(point));
            mGoogleMap.animateCamera(CameraUpdateFactory.zoomTo(12));

            drawMarker(point);
        }
    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub
    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub
    }

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

13. Update the file AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="in.wptrafficanalyzer.locationroutemylocationv2"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <uses-permission android:name="android.permission.INTERNET"/>

    <permission
        android:name="in.wptrafficanalyzer.locationroutemylocationv2.permission.MAPS_RECEIVE"
        android:protectionLevel="signature" />

    <uses-permission android:name="in.wptrafficanalyzer.locationroutemylocationv2.permission.MAPS_RECEIVE" />

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="in.wptrafficanalyzer.locationroutemylocationv2.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="YOUR_ANDROID_API_KEY"/>

    </application>

</manifest>

Note : Please ensure that “YOUR_ANDROID_API_KEY” at line 46 is replaced with the api key obtained in Step 8.

14. Screenshot of the application

Figure 7 : Showing route from my location to a destination location

15. Download Source Code

How to hire me?

I am George Mathew, working as software architect and Android app developer at wptrafficanalyzer.in

You can hire me on hourly basis or on project basis for Android applications development.

For hiring me, please mail your requirements to info@wptrafficanalyzer.in.

My other blogs
store4js.blogspot.com

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Tags: asynchronous, ASyncTask, google directions api, Google Map Android API V2, LocationManager, LOCATION_SERVICE, route, SupportMapFragment