Venkata Venkata - 15 days ago 6
Android Question

How to display duration using Google Maps?

I am trying to display to the user just the duration between two locations using latitude and longitude. I am having trouble with permissions which I am not sure how to handle it.

Here is my doInBackground code:

protected String[] doInBackground(String... params) {


try {
LocationManager locationManager = (LocationManager) MyCustomHomeActivity.this
.getSystemService(LOCATION_SERVICE);

// getting GPS status
boolean isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);

// getting network status
boolean isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
} else {

// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {

if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}

} catch (Exception e) {
e.printStackTrace();
}


String shuLat = "41.2207188";
String shuLong = "-73.24168179999999";
String forecastJsonStr = null;

String myUrlSetup = "https://maps.googleapis.com/maps/api/directions/json?origin="+latitude + "," + longitude +"&destination="+shuLat +"," + shuLong + "&departure_time=now&traffic_model=best_guess&key=AIzaSyB6l8vrnspw2-1Q_cnzO03JlAsIOMl-7bs";
HttpURLConnection urlConnection = null;
BufferedReader reader = null;

try {

URL url;
url = new URL(myUrlSetup);


// Create the request to GoogleMapAPI, and open the connection
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();

// Read the input stream into a String
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
// Nothing to do.
return null;
}
System.out.println("I am in doInBackground step3");
reader = new BufferedReader(new InputStreamReader(inputStream));

String line;
while ((line = reader.readLine()) != null) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
buffer.append(line + "\n");
}

if (buffer.length() == 0) {
// Stream was empty. No point in parsing.
return null;
}
forecastJsonStr = buffer.toString();

Log.v(LOG_TAG, "Forecast string: " + forecastJsonStr);
} catch (IOException e) {
Log.e(LOG_TAG, "Error ", e);
// If the code didn't successfully get the weather data, there's no point in attemping
// to parse it.
return null;
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "Error closing stream", e);
}
}
}

try {
System.out.println("I am just in front of calling getDurationDataFromJson");
return getDurationDataFromJson(forecastJsonStr);
} catch (JSONException e) {
Log.e(LOG_TAG, e.getMessage(), e);
e.printStackTrace();
}
return new String[0];
}//end doInBackground


Here is my getDurationDataFromJSON code:

private String[] getDurationDataFromJson(String forecastJsonStr)
throws JSONException {

// These are the names of the JSON objects that need to be extracted.
final String OWM_ROUTES = "routes";
final String OWM_LEGS = "legs";
final String OWM_DURATION = "duration";
final String OWM_TEXT = "text";


String[] resultStrs = new String[0];
String duration;

JSONObject durationJson = new JSONObject(forecastJsonStr);

JSONArray routeArray = durationJson.getJSONArray(OWM_ROUTES);

JSONArray legArray = routeArray.getJSONObject(0).getJSONArray(OWM_LEGS);

//Duration
JSONObject durationObj = legArray.getJSONObject(0).getJSONObject(OWM_DURATION);

duration = durationObj.getString(OWM_TEXT);

resultStrs[0] = duration;

System.out.println("Duration is: " + duration);
for (String s : resultStrs) {
System.out.println("Duration entry: " + s);
Log.v(LOG_TAG, "Duration entry: " + s);
}
return resultStrs;

}


Trouble I am facing is the following part in doInBackGround code:

location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);


Error is:

Call requires permission which may be rejected by user: code should explicitly check to see if permission is available(with `check permission`) or explicitly handle a potential `SecurityException`.


I am not sure if I am going in the right direction. Please guide me through this.

Answer

With Android API level (23), permissions are requested at running time, here you have de official documentation:

https://developer.android.com/training/permissions/requesting.html

Basically, you need to check if the device Android API level is >= 23, and if so, request the required permissions. Try something like this:

if ( Build.VERSION.SDK_INT >= 23)
        //Ask for needed permissions following the docs mentioned above
}

I hope this helps!