i try to build an app that show a route and draw it, for after calculate distance an travel time, for all points A + B + C + D... but it show this error, i don't know how fix.
i looking for similar answers, but no response for this case
TAL EXCEPTION: main
Process: com.elgeos.wayp.wa, PID: 17963
java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
at com.elgeos.wayp.wa.PathGoogleMapActivity$ParserTask.onPostExecute(PathGoogleMapActivity.java:139)
at com.elgeos.wayp.wa.PathGoogleMapActivity$ParserTask.onPostExecute(PathGoogleMapActivity.java:113)
at android.os.AsyncTask.finish(AsyncTask.java:651)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:668)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Below i attach my full java activity, Android Studio show me all ok, but when i debug app, fail app
package com.elgeos.wayp.wa;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.json.JSONObject;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
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 PathGoogleMapActivity extends FragmentActivity implements OnMapReadyCallback {
private static final LatLng LOWER_MANHATTAN = new LatLng(40.722543,
-73.998585);
private static final LatLng BROOKLYN_BRIDGE = new LatLng(40.7057, -73.9964);
private static final LatLng WALL_STREET = new LatLng(40.7064, -74.0094);
GoogleMap mMap;
final String TAG = "PathGoogleMapActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_path_google_map);
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
MarkerOptions options = new MarkerOptions();
options.position(LOWER_MANHATTAN);
options.position(BROOKLYN_BRIDGE);
options.position(WALL_STREET);
mMap.addMarker(options);
String url = getMapsApiDirectionsUrl();
ReadTask downloadTask = new ReadTask();
downloadTask.execute(url);
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(BROOKLYN_BRIDGE,
13));
addMarkers();
}
private String getMapsApiDirectionsUrl() {
String waypoints = "waypoints=optimize:true|"
+ LOWER_MANHATTAN.latitude + "," + LOWER_MANHATTAN.longitude
+ "|" + "|" + BROOKLYN_BRIDGE.latitude + ","
+ BROOKLYN_BRIDGE.longitude + "|" + WALL_STREET.latitude + ","
+ WALL_STREET.longitude;
String sensor = "sensor=false";
String params = waypoints + "&" + sensor;
String output = "json";
String url = "https://maps.googleapis.com/maps/api/directions/"
+ output + "?" + params;
return url;
}
private void addMarkers() {
if (mMap != null) {
mMap.addMarker(new MarkerOptions().position(BROOKLYN_BRIDGE)
.title("First Point"));
mMap.addMarker(new MarkerOptions().position(LOWER_MANHATTAN)
.title("Second Point"));
mMap.addMarker(new MarkerOptions().position(WALL_STREET)
.title("Third Point"));
}
}
private class ReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... url) {
String data = "";
try {
HttpConnection http = new HttpConnection();
data = http.readUrl(url[0]);
} catch (Exception e) {
Log.d("Background Task", e.toString());
}
return data;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
new ParserTask().execute(result);
}
}
private class ParserTask extends
AsyncTask<String, Integer, List<List<HashMap<String, String>>>> {
@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]);
PathJSONParser parser = new PathJSONParser();
routes = parser.parse(jObject);
} catch (Exception e) {
e.printStackTrace();
}
return routes;
}
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> routes) {
ArrayList<LatLng> points = null;
PolylineOptions polyLineOptions = null;
// traversing through routes
for (int i = 0; i < routes.size(); i++) {
points = new ArrayList<LatLng>();
polyLineOptions = new PolylineOptions();
List<HashMap<String, String>> path = routes.get(i);
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);
}
polyLineOptions.addAll(points);
polyLineOptions.width(2);
polyLineOptions.color(Color.BLUE);
}
mMap.addPolyline(polyLineOptions);
}
}
}
