Google Maps Android V2 and Direction API

Question

I'm developing an app where i need to know the path between the current user posistion and a point of interest.

I'm using android 2.3.3, google maps android v2 and direction api. My problem is that all the code i have found is for the old version of the maps, and I also tried to adapt the code but i failed. I try to change GeoPoint (not supported in this new versione) in LatLng. the problem is that i can't display the path, to do it i create a new polyline and i add it to the map.

i post my code:

Parser:

public interface Parser {
    public Route parse();
}

XMLParser

public class XMLParser {
    // names of the XML tags
    protected static final String MARKERS = "markers";
    protected static final String MARKER = "marker";

    protected URL feedUrl;

    protected XMLParser(final String feedUrl) {
            try {
                    this.feedUrl = new URL(feedUrl);
            } catch (MalformedURLException e) {
                    Log.e(e.getMessage(), "XML parser - " + feedUrl);
            }
    }

    protected InputStream getInputStream() {
            try {
                    return feedUrl.openConnection().getInputStream();
            } catch (IOException e) {
                    Log.e(e.getMessage(), "XML parser - " + feedUrl);
                    return null;
            }
    }
}

JsonParser (parse the google direction json)

public class JsonParser extends XMLParser implements Parser {
    /** Distance covered. **/
    private int distance;

    public JsonParser(String feedUrl) {
        super(feedUrl);
    }

    /**
     * Parses a url pointing to a Google JSON object to a Route object.
     * @return a Route object based on the JSON object.
     */

    public Route parse() {
        // turn the stream into a string
        final String result = convertStreamToString(this.getInputStream());
        //Create an empty route
        final Route route = new Route();
        //Create an empty segment
        final Segment segment = new Segment();
        try {
            //Tranform the string into a json object
            final JSONObject json = new JSONObject(result);
            //Get the route object
            final JSONObject jsonRoute = json.getJSONArray("routes").getJSONObject(0);
            //Get the leg, only one leg as we don't support waypoints
            final JSONObject leg = jsonRoute.getJSONArray("legs").getJSONObject(0);
            //Get the steps for this leg
            final JSONArray steps = leg.getJSONArray("steps");
            //Number of steps for use in for loop
            final int numSteps = steps.length();
            //Set the name of this route using the start & end addresses
            route.setName(leg.getString("start_address") + " to " + leg.getString("end_address"));
            //Get google's copyright notice (tos requirement)
            route.setCopyright(jsonRoute.getString("copyrights"));
            //Get the total length of the route.
            route.setLength(leg.getJSONObject("distance").getInt("value"));
            //Get any warnings provided (tos requirement)
            if (!jsonRoute.getJSONArray("warnings").isNull(0)) {
                route.setWarning(jsonRoute.getJSONArray("warnings").getString(0));
            }
            /* Loop through the steps, creating a segment for each one and
             * decoding any polylines found as we go to add to the route object's
             * map array. Using an explicit for loop because it is faster!
             */
            for (int i = 0; i < numSteps; i++) {
                //Get the individual step
                final JSONObject step = steps.getJSONObject(i);
                //Get the start position for this step and set it on the segment
                final JSONObject start = step.getJSONObject("start_location");
                final LatLng position = new LatLng(start.getDouble("lat"), start.getDouble("lng"));
                segment.setPoint(position);
                //Set the length of this segment in metres
                final int length = step.getJSONObject("distance").getInt("value");
                distance += length;
                segment.setLength(length);
                segment.setDistance(distance/1000);
                //Strip html from google directions and set as turn instruction
                segment.setInstruction(step.getString("html_instructions").replaceAll("<(.*?)*>", ""));
                //Retrieve & decode this segment's polyline and add it to the route.
                route.addPoints(decodePolyLine(step.getJSONObject("polyline").getString("points")));
                //Push a copy of the segment to the route
                route.addSegment(segment.copy());
            }
        } catch (JSONException e) {
            Log.e(e.getMessage(), "Google JSON Parser - " + feedUrl);
        }
        return route;
    }

    /**
     * Convert an inputstream to a string.
     * @param input inputstream to convert.
     * @return a String of the inputstream.
     */

    private static String convertStreamToString(final InputStream input) {
        final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
        final StringBuilder sBuf = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sBuf.append(line);
            }
        } catch (IOException e) {
            Log.e(e.getMessage(), "Google parser, stream2string");
        } finally {
            try {
                input.close();
            } catch (IOException e) {
                Log.e(e.getMessage(), "Google parser, stream2string");
            }
        }
        return sBuf.toString();
    }

    /**
     * Decode a polyline string into a list of LatLng.
     * @param poly polyline encoded string to decode.
     * @return the list of GeoPoints represented by this polystring.
     */

    private List<LatLng> decodePolyLine(final String poly) {
        int len = poly.length();
        int index = 0;
        List<LatLng> decoded = new LinkedList<LatLng>();
        int lat = 0;
        int lng = 0;

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

            decoded.add(new LatLng((lat / 1E5),(lng / 1E5)));
        }

        return decoded;
    }
}

Route (to save json info)

public class Route {
    private String name;
    private final List<LatLng> points;
    private List<Segment> segments;
    private String copyright;
    private String warning;
    private String country;
    private int length;
    private String polyline;

    public Route() {
        points = new LinkedList<LatLng>();
        segments = new LinkedList<Segment>();
    }

    public void addPoint(final LatLng p) {
        points.add(p);
    }

    public void addPoints(final List<LatLng> points) {
        this.points.addAll(points);
    }

    public List<LatLng> getPoints() {
        return points;
    }

    public void addSegment(final Segment s) {
        segments.add(s);
    }

    public List<Segment> getSegments() {
        return segments;
    }

    /**
     * @param name the name to set
     */
     public void setName(final String name) {
        this.name = name;
    }

    /**
     * @return the name
     */
     public String getName() {
         return name;
     }

     /**
      * @param copyright the copyright to set
      */
     public void setCopyright(String copyright) {
         this.copyright = copyright;
     }

     /**
      * @return the copyright
      */
     public String getCopyright() {
         return copyright;
     }

     /**
      * @param warning the warning to set
      */
     public void setWarning(String warning) {
         this.warning = warning;
     }

     /**
      * @return the warning
      */
     public String getWarning() {
         return warning;
     }

     /**
      * @param country the country to set
      */
     public void setCountry(String country) {
         this.country = country;
     }

     /**
      * @return the country
      */
     public String getCountry() {
         return country;
     }

     /**
      * @param length the length to set
      */
     public void setLength(int length) {
         this.length = length;
     }

     /**
      * @return the length
      */
     public int getLength() {
         return length;
     }


     /**
      * @param polyline the polyline to set
      */
     public void setPolyline(String polyline) {
         this.polyline = polyline;
     }

     /**
      * @return the polyline
      */
     public String getPolyline() {
         return polyline;
     }

}

Segment:

public class Segment {
    /** Points in this segment. **/
    private LatLng start;
    /** Turn instruction to reach next segment. **/
    private String instruction;
    /** Length of segment. **/
    private int length;
    /** Distance covered. **/
    private double distance;

    /**
     * Create an empty segment.
     */

    public Segment() {
    }


    /**
     * Set the turn instruction.
     * @param turn Turn instruction string.
     */

    public void setInstruction(final String turn) {
            this.instruction = turn;
    }

    /**
     * Get the turn instruction to reach next segment.
     * @return a String of the turn instruction.
     */

    public String getInstruction() {
            return instruction;
    }

    /**
     * Add a point to this segment.
     * @param point LatLng to add.
     */

    public void setPoint(LatLng point) {
            start = point;
    }

    /** Get the starting point of this 
     * segment.
     * @return a LatLng
     */

    public LatLng startPoint() {
            return start;
    }

    /** Creates a segment which is a copy of this one.
     * @return a Segment that is a copy of this one.
     */

    public Segment copy() {
            final Segment copy = new Segment();
            copy.start = start;
            copy.instruction = instruction;
            copy.length = length;
            copy.distance = distance;
            return copy;
    }

    /**
     * @param length the length to set
     */
    public void setLength(final int length) {
            this.length = length;
    }

    /**
     * @return the length
     */
    public int getLength() {
            return length;
    }

    /**
     * @param distance the distance to set
     */
    public void setDistance(double distance) {
            this.distance = distance;
    }

    /**
     * @return the distance
     */
    public double getDistance() {
            return distance;
    }

}

My MainActivity (there are 326 code line because of user localization, you can find it on google developer site, so we can just suppose to have two static point A and B and I want to go from A to B):

public class MainActivity extends FragmentActivity{
    private GoogleMap map;
    private Marker currentLocation;
    private PolylineOptions pathLine;
    private LatLng imhere = new LatLng(41.8549038,12.4618208);
        private LatLng poi = new LatLng(41.89000,12.49324);


    private LocationManager mLocationManager;
    private Handler mHandler;
    private boolean mUseBoth;
    private Context context;
    // Keys for maintaining UI states after rotation.
    private static final String KEY_BOTH = "use_both";
    // UI handler codes.
    private static final int UPDATE_LATLNG = 2;

    private static final int FIVE_SECONDS = 5000;
    private static final int THREE_METERS = 3;
    private static final int TWO_MINUTES = 1000 * 60 * 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();
        Marker colosseoMarker  = map.addMarker(new MarkerOptions()
        .position(colosseo)
        .title("Start")
        .snippet("poi")
        .icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher)));

                Marker current pos = map.addMarker(new MarkerOptions()
        .position(imhere)
        .title("i'm here")
        .snippet("here!")
        .icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher)));

        context =this ;
        map.setOnMarkerClickListener(new OnMarkerClickListener() {

            @Override
            public boolean onMarkerClick(Marker marker) {
                final String[] options = {"Calcola il Percorso"};
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setTitle("Ottieni Informazioni aggiuntive");
                builder.setPositiveButton("Calcola Percorso",new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog,int id) {
                        LatLng start = new LatLng(imhere.latitude,imhere.longitude);
                        LatLng dest = new LatLng(poi.latitude, poi.longitude);
                        Route route = drawPath(start, dest);

                        List<LatLng> list= route.getPoints();

if(pathLine!= null) pathline =null;                         
pathLine = new PolylineOptions();

                        pathLine.addAll(list);
                        pathLine.color(Color.rgb(0,191,255));

                        map.addPolyline(pathLine);

                    }
                  });

                AlertDialog alert = builder.create();
                alert.show();
                Toast.makeText(MainActivity.this, marker.getSnippet(),Toast.LENGTH_SHORT).show();
                return true;
            }
        });


                    map.animateCamera(CameraUpdateFactory.newLatLngZoom(imhere, 12));
                }
            }
        };
        // Get a reference to the LocationManager object.
        mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    }


     private Route drawPath(LatLng start, LatLng dest) {
            Parser parser;
            String jsonURL = "http://maps.google.com/maps/api/directions/json?";
            final StringBuffer sBuf = new StringBuffer(jsonURL);
            sBuf.append("origin=");
            sBuf.append(start.latitude);
            sBuf.append(',');
            sBuf.append(start.longitude);
            sBuf.append("&destination=");
            sBuf.append(dest.latitude);
            sBuf.append(',');
            sBuf.append(dest.longitude);
            sBuf.append("&sensor=true&mode=walking");
            parser = new JsonParser(sBuf.toString());
            Route r =  parser.parse();
            return r;
        }
}

every suggestion is well accepted

Answer 1

If you don't need custom code try this lib https://github.com/jd-alexander/Google-Directions-Android only a few lines of code to do what you need.