How to get the time of public transport in maps api

Question

I am building a personal project to familiarise myself with API calling etc.

I have the following function:

    public void calculateDistance(House house) {

    DirectionsApiRequest apiRequest = DirectionsApi.newRequest(geoApiContext);
    apiRequest.origin(new LatLng(house.getLat(), house.getLon()));
    apiRequest.destination(biminghamInternationStationLonLat);
    apiRequest.mode(TravelMode.TRANSIT);
    apiRequest.setCallback(new com.google.maps.PendingResult.Callback<DirectionsResult>() {
        @Override
        public void onResult(DirectionsResult result) {
            DirectionsRoute[] routes = result.routes;
            System.out.println("Printing out the results for " + house.getUrlListing());

            for(int i =0 ; i < routes.length; i++)
            {
                DirectionsRoute route = routes[i];
                System.out.println(route);
            }
        }

        @Override
        public void onFailure(Throwable e) {

        }
    });
}

What this function does is gets the latitude and longitude of the custom House object I am providing, and essentially finds how long it takes to reach birmingham international station via public transport (hence the TRANSIT mode in the apiRequest).

But I'm not sure if I am using it correctly? When I go on google maps website and check how long it'll take for me to get to birmingham international station from the location of the house; I get results varying from 30-35 mins, okay. But when I try calling the above code it prints the following:

[DirectionsRoute: "", 1 legs, waypointOrder=[], bounds=[52.48039080,-1.72493200, 52.45082300,-1.78392750], 1 warnings]

I'm not sure how I can get the time it takes via public transport from the api. I am using the Directions API.. not sure if im using the wrong API but when looking at what API to use, this was described what I needed..

score 1 · Accepted Answer · answered Oct 25 '20 at 00:03

I can see that you are using the Java Client for Google Maps Services. In order to understand how to work with the library I can suggest having a look at the JavaDoc that located at

https://www.javadoc.io/doc/com.google.maps/google-maps-services/latest/index.html

Checking the JavaDoc documentation you will see that DirectionsRoute object contains an array of DirectionsLeg[] and the direction leg in its turn has a field with Duration object. So you need to loop through all legs of the route and sum up leg's duration that will give you a complete route duration in seconds.

Referring to the synchronous calls in the Java client library, you can do requests synchronously calling the await() method of the request.

Have a look at the following example that is based on your code. It shows how to get transit directions synchronously and calculate the duration in seconds for the first route

import com.google.maps.GeoApiContext;
import com.google.maps.DirectionsApiRequest;
import com.google.maps.DirectionsApi;
import com.google.maps.model.DirectionsResult;
import com.google.maps.model.DirectionsRoute;
import com.google.maps.model.DirectionsLeg;
import com.google.maps.model.LatLng;
import com.google.maps.model.TravelMode;


class Main {
  public static void main(String[] args) {
    GeoApiContext context = new GeoApiContext.Builder()
    .apiKey("YOUR_API_KEY")
    .build();

    DirectionsApiRequest apiRequest = DirectionsApi.newRequest(context);
    apiRequest.origin(new LatLng(41.385064,2.173403));
    apiRequest.destination(new LatLng(40.416775,-3.70379));
    apiRequest.mode(TravelMode.TRANSIT);

    long duration = 0;
  
    try {
      DirectionsResult res = apiRequest.await();

      //Loop through legs of first route and get duration
      if (res.routes != null && res.routes.length > 0) {
          DirectionsRoute route = res.routes[0];

          if (route.legs !=null) {
              for(int i=0; i<route.legs.length; i++) {
                  DirectionsLeg leg = route.legs[i];
                  duration += leg.duration.inSeconds;
              }    
          }
      }
    } catch(Exception ex) {
      System.out.println(ex.getMessage());
    }

    System.out.println("Duration (sec): " + duration);
  }
}

Enjoy!

score 0 · Answer 2 · answered Oct 24 '20 at 15:09

0

The duration of travel is in the legs:

duration indicates the total duration of this leg, as a Duration object of the following form:

value indicates the duration in seconds.

text contains a string representation of the duration.
These fields may be undefined if the duration is unknown.

If there are multiple legs in the response, you can get the total duration by adding up the value for each leg.

Related questions: Google Maps API V3 display duration and distance in info window

answered Oct 24 '20 at 15:09

geocodezip

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Thanks! Also a quick one, the method 'setCallback' in the code snippet in my question is non blocking i.e. it starts it's own thread I believe. I need it to be blocking as the previous code relies on the result. Any suggestions as to how i can prevent the code from going forwards until it gets the result of the duration? – tcho1506996 Oct 24 '20 at 15:29
The service call is asynchronous, use a promise or use the data in the callback function when/where it is available. – geocodezip Oct 24 '20 at 17:44

How to get the time of public transport in maps api

2 Answers2