android : get turn by turn direction of route between two geo locations

Question

I want to show turn by turn directions between two locations. I tried

 uri = "http://maps.google.com/maps?saddr="
                + "lat1" + ","
                +  "lon1" + "&daddr="
                + "lat2" + "," + "long2";
        Intent intent = new Intent(android.content.Intent.ACTION_VIEW,
                Uri.parse(uri));

It gives the route. But i dont want to open a browser and show. Instead is there a way to get the route so that it can be displayed in my own layout. For ex in text views.

Answer 1

These code i wrote in my graduation project so they're not optimized.

1. MapService class: I parser data response from google map.

   public class MapService {
   public static final String TAG = "[MapService]";
   public static final String GET_DIRECTION_URL = "http://maps.google.com/maps/api/directions/json?" + "origin=%f,%f" + "&destination=%f,%f" + "&sensor=true&language=en&units=metric";
   
   public static DirectionResult getDirectionResult(double latitude1, double longtitude1, double latitude2, double longtitude2) {
       String url = String.format(GET_DIRECTION_URL, latitude1, longtitude1, latitude2, longtitude2);
       Log.d("URL", url);
       // parse direction
       DirectionParser directionParser = new DirectionParser() {
           @Override
           public void onSuccess(JSONObject json) throws JSONException {
               // process response status
               String status = json.getString("status");
               if (!status.equals("OK")) {
                   String error = null;
   
                   if (status.equals("NOT_FOUND") || status.equals("ZERO_RESULTS")) {
                       error = Global.application.getString(R.string.errCantGetDirection);
                   } else {
                       error = Global.application.getString(R.string.errGetDirection);
                   }
   
                   result.instructions = new String[] { error };
                   result.hasError = true;
                   return;
               }
   
               /*
                * routes[] legs[] steps[] html_instructions
                */
               JSONArray arrRoutes = json.getJSONArray("routes");
   
               // no routes found
               if (arrRoutes.length() == 0) {
                   result.instructions = new String[] { Global.application.getString(R.string.errCantGetDirection) };
                   result.hasError = true;
                   return;
               }
   
               JSONArray arrLegs = arrRoutes.getJSONObject(0).getJSONArray("legs");
               JSONObject firstLeg = arrLegs.getJSONObject(0);
               JSONArray arrSteps = firstLeg.getJSONArray("steps");
               int len = arrSteps.length();
               result.instructions = new String[len];
               result.points = new LinkedList<GeoPoint>();
               JSONObject leg = null;
   
               // get instructions
               for (int i = 0; i < len; ++i) {
                   leg = arrSteps.getJSONObject(i);
                   // location = leg.getJSONObject("start_location");
                   String encoded = leg.getJSONObject("polyline").getString("points");
                   result.points.addAll(decodePoly(encoded));
   
                   result.instructions[i] = Html.fromHtml(leg.getString("html_instructions")).toString();
                   Log.d("html_instructions", "" + Html.fromHtml(leg.getString("html_instructions")));
                   // result.points[i] = new GeoPoint(
                   // (int) (location.getDouble("lat") * 1E6),
                   // (int) (location.getDouble("lng") * 1E6));
               }
   
               // location = leg.getJSONObject("end_location");
               // result.points[len] = new GeoPoint(
               // (int) (location.getDouble("lat") * 1E6),
               // (int) (location.getDouble("lng") * 1E6));
   
               // distance and duration info
               JSONObject distance = firstLeg.getJSONObject("distance");
               if (distance != null) {
                   result.distance = distance.getString("text");
               }
               JSONObject duration = firstLeg.getJSONObject("duration");
               if (duration != null) {
                   result.duration = duration.getString("text");
               }
           }
   
           @Override
           public void onFailure(String message) {
               String error = "Error";
   
               result.instructions = new String[] { error };
               result.hasError = true;
           }
       };
   
       // return direction result
       RestClient.getData(url, directionParser);
       return directionParser.result;
   }
   
   private static List<GeoPoint> decodePoly(String encoded) {
       List<GeoPoint> poly = new ArrayList<GeoPoint>();
       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;
   
           GeoPoint p = new GeoPoint((int) (((double) lat / 1E5) * 1E6), (int) (((double) lng / 1E5) * 1E6));
           poly.add(p);
       }
   
       return poly;
   }
   
       }
   

2. Direction parser and direction result

   public class DirectionParser extends JSONParser {
   public DirectionResult result = new DirectionResult();
   
   protected int jsonType = JSONParser.GOOGLE_DIRECTION_JSON;
   
   public DirectionParser() {
       jsonType = JSONParser.GOOGLE_DIRECTION_JSON;
   }
   
   @Override
   public void onFailure(String message) {
   }
   
   @Override
   public void onSuccess(JSONObject json) throws JSONException {
   }
   }
   
   public class DirectionResult {
    public String[] instructions;
    public List<GeoPoint> points;
    public String duration;
    public String distance;
    public boolean hasError = false;
   }
   

3. What you want is the instruction of DirectionResult. You can simple create an array adapter with string array

    instructions = directionResult.instructions;// DirectionResult you got from MapService.
       ArrayAdapter<String> adapter1 = new ArrayAdapter<String>(DirectionListActivity.this, android.R.layout.simple_list_item_1, instructions);
                    listDirection.setAdapter(adapter1);
   

Update: Another parser i found Google-Maps-Directions-API-Java-Parser

Answer 2

Check out GreatMaps. They have logic for retrieving routes. Its C# based, just use their logic and write the equivalent in Java.

http://greatmaps.codeplex.com/