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I'm trying to use the google maps API to fetch direction times. I'm hoping to create a url, get the JSON response, and then examine that response for travel duration. After I create the JSON object, I have trouble navigating it. To me, this indicates that I have either messed up getting the response or navigating the JSON object. I'd appreciate it if you could peek at the bits and pieces of code I have stitched together from tutorials around the web.

This code is intended to get the response. It's surrounded by a try/catch and it hasn't triggered any errors.

      String stringUrl = <URL GOES HERE>;

      URL url = new URL(stringUrl);
      HttpURLConnection httpconn = (HttpURLConnection)url.openConnection();
      if (httpconn.getResponseCode() == HttpURLConnection.HTTP_OK)
      {
          BufferedReader input = new BufferedReader(new InputStreamReader(httpconn.getInputStream()),8192);
          String strLine = null;
          while ((strLine = input.readLine()) != null)
          {
              response.append(strLine);
          }
          input.close();
      }
      String jsonOutput = response.toString();

This code is intended to take that output and parse it into the final string, duration, as inspired by this stackoverflow answer for a similar question. 

        JSONObject jsonObject = new JSONObject(jsonOutput);
        JSONObject routeObject = jsonObject.getJSONObject("routes");
        JSONObject legsObject = routeObject.getJSONObject("legs");
        JSONObject durationObject = legsObject.getJSONObject("duration"); 
        String duration = durationObject.getString("text");

I'm catching a JSON exception on the second line of the second block. Can anyone help to fix this? Or perhaps suggest a simpler way to get the same data?

EDIT: thanks to the first helpful answer here (from aromero), the latter half now looks like:

    JSONObject jsonObject = new JSONObject(responseText);
    JSONArray routeObject = jsonObject.getJSONArray("routes");
    JSONArray legsObject = routeObject.getJSONArray(2); ***error***
    JSONObject durationObject = legsObject.getJSONObject(1);
        String duration = durationObject.getString("text");

But it is still throwing a JSON exception, only now it's after the third line. I'm sure this is embarrassingly easy to fix, but I would really appreciate some help.

The relevant part of an example JSON file is shown below:

{
   "routes" : [
      {
         "bounds" : {
            "northeast" : {
               "lat" : 34.092810,
               "lng" : -118.328860
            },
            "southwest" : {
               "lat" : 33.995590,
               "lng" : -118.446040
            }
         },
         "copyrights" : "Map data ©2011 Google",
         "legs" : [
            {
               "distance" : {
                  "text" : "12.9 mi",
                  "value" : 20807
               },
               "duration" : {
                  "text" : "27 mins",
                  "value" : 1619
               },
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user714403
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2 Answers2

15

"routes" is an array, instead of using getJSONObject, use getJSONArray

"legs" is an array also.

JSONObject jsonObject = new JSONObject(responseText);

// routesArray contains ALL routes
JSONArray routesArray = jsonObject.getJSONArray("routes");
// Grab the first route
JSONObject route = routesArray.getJSONObject(0);
// Take all legs from the route
JSONArray legs = route.getJSONArray("legs");
// Grab first leg
JSONObject leg = legs.getJSONObject(0);

JSONObject durationObject = leg.getJSONObject("duration");
String duration = durationObject.getString("text");
aromero
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  • I think you've identified what I'm doing wrong. Still ironing out the specifics. I'll post back when I fix it, unless someone beats me to it. – user714403 Aug 30 '11 at 00:17
  • Routes is an array, I assume google is returning you a list of possible routes. So you need to grab one of them, or do something on all of them. What are you trying to do? – aromero Aug 30 '11 at 00:21
  • Awesome! Thanks for the edit to your original answer, I really appreciate the hand holding. I really didn't understand the syntax/spacing of the JSON and you've made it wonderfully clear. Many thanks! – user714403 Aug 30 '11 at 00:33
2

I was also trying to use the Direction Api of Google in Android. So I made an open source project to help doing that. You can find it here:https://github.com/MathiasSeguy-Android2EE/GDirectionsApiUtils

How it works, definitly simply:

public class MainActivity extends ActionBarActivity implements DCACallBack{
/**
 * Get the Google Direction between mDevice location and the touched location using the     Walk
 * @param point
 */
private void getDirections(LatLng point) {
     GDirectionsApiUtils.getDirection(this, startPoint, endPoint, GDirectionsApiUtils.MODE_WALKING);
}

/*
 * The callback
 * When the directions is built from the google server and parsed, this method is called and give you the expected direction
 */
@Override
public void onDirectionLoaded(List<GDirection> directions) {        
    // Display the direction or use the DirectionsApiUtils
    for(GDirection direction:directions) {
        Log.e("MainActivity", "onDirectionLoaded : Draw GDirections Called with path " + directions);
        GDirectionsApiUtils.drawGDirection(direction, mMap);
    }
}
Mathias Seguy Android2ee
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