How to use Google QPX API with Java for flight sea

I am trying to build a simple Java code that obtains flight options using Google QPX API, for the flight from New York to London. I signed up with Google and got API_key.

I read the documentation, but unfortunately, I couldn't find any example that show me how to do it.

Here what I tried so far:

import com.google.api.services.qpxExpress.model.*;
import java.util.*;

public class Main 
{
    public static void main(String[] args) 
    {   
        // Passengers
        PassengerCounts passengers = new PassengerCounts();
        passengers.setAdultCount(2);

        // Slice
        List<SliceInput> slices = new ArrayList<SliceInput>();

        SliceInput slice = new SliceInput();
        slice.setOrigin("JFK"); // John Kennedy Airport in Ney York
        slice.setDestination("LHR"); // London Heathrow
        slice.setDate("2015-07-01");
        slices.add(slice);


        // Options request
        TripOptionsRequest tripOptions = new TripOptionsRequest(); 
        tripOptions.setPassengers(passengers);
        tripOptions.setSlice(slices);


        // Search request
        TripsSearchRequest tripSearchReq = new TripsSearchRequest();
        tripSearchReq.setRequest(tripOptions);

        // Next steps?
        // Setting up QPXExpress?

    }
}

I will appreciate it if someone can help me to complete the code. Thanks in advance.

This is a simple code, successfully tested, hope it helps

package com.airline.api;

import java.io.IOException;
import java.util.*;

import javax.swing.text.View;

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.qpxExpress.QPXExpressRequestInitializer;
import com.google.api.services.qpxExpress.QPXExpress;
import com.google.api.services.qpxExpress.model.FlightInfo;
import com.google.api.services.qpxExpress.model.LegInfo;
import com.google.api.services.qpxExpress.model.PassengerCounts;
import com.google.api.services.qpxExpress.model.PricingInfo;
import com.google.api.services.qpxExpress.model.SegmentInfo;
import com.google.api.services.qpxExpress.model.SliceInfo;
import com.google.api.services.qpxExpress.model.TripOption;
import com.google.api.services.qpxExpress.model.TripOptionsRequest;
import com.google.api.services.qpxExpress.model.TripsSearchRequest;
import com.google.api.services.qpxExpress.model.SliceInput;
import com.google.api.services.qpxExpress.model.TripsSearchResponse;

public class AirlineReservation {

    /**
     * @param args
     */


      private static final String APPLICATION_NAME = "MyFlightApplication";

      private static final String API_KEY = "AIzaSyDnBCdsmTnrL5XFrO2TjJyvFioswjakNYU";

      /** Global instance of the HTTP transport. */
      private static HttpTransport httpTransport;

      /** Global instance of the JSON factory. */
      private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();




    public static void main(String[] args) {
        // TODO Auto-generated method stub

         try {
              httpTransport = GoogleNetHttpTransport.newTrustedTransport();


              PassengerCounts passengers= new PassengerCounts();
                passengers.setAdultCount(1);

                List<SliceInput> slices = new ArrayList<SliceInput>();

                SliceInput slice = new SliceInput();
                slice.setOrigin("NYC"); 
                slice.setDestination("LGA"); 
                slice.setDate("2015-04-29");
                slices.add(slice);

                TripOptionsRequest request= new TripOptionsRequest();
                request.setSolutions(10);
                request.setPassengers(passengers);
                request.setSlice(slices);

                TripsSearchRequest parameters = new TripsSearchRequest();
                parameters.setRequest(request);
                QPXExpress qpXExpress= new QPXExpress.Builder(httpTransport, JSON_FACTORY, null).setApplicationName(APPLICATION_NAME)
                        .setGoogleClientRequestInitializer(new QPXExpressRequestInitializer(API_KEY)).build();

                TripsSearchResponse list= qpXExpress.trips().search(parameters).execute();
                List<TripOption> tripResults=list.getTrips().getTripOption();

                String id;

                for(int i=0; i<tripResults.size(); i++){
                    //Trip Option ID
                    id= tripResults.get(i).getId();
                    System.out.println("id "+id);

                    //Slice
                    List<SliceInfo> sliceInfo= tripResults.get(i).getSlice();
                    for(int j=0; j<sliceInfo.size(); j++){
                        int duration= sliceInfo.get(j).getDuration();
                        System.out.println("duration "+duration);
                        List<SegmentInfo> segInfo= sliceInfo.get(j).getSegment();
                        for(int k=0; k<segInfo.size(); k++){
                            String bookingCode= segInfo.get(k).getBookingCode();
                            System.out.println("bookingCode "+bookingCode);
                            FlightInfo flightInfo=segInfo.get(k).getFlight();
                            String flightNum= flightInfo.getNumber();
                            System.out.println("flightNum "+flightNum);
                            String flightCarrier= flightInfo.getCarrier();
                            System.out.println("flightCarrier "+flightCarrier);
                            List<LegInfo> leg=segInfo.get(k).getLeg();
                            for(int l=0; l<leg.size(); l++){
                                String aircraft= leg.get(l).getAircraft();
                                System.out.println("aircraft "+aircraft);
                                String arrivalTime= leg.get(l).getArrivalTime();
                                System.out.println("arrivalTime "+arrivalTime);
                                String departTime=leg.get(l).getDepartureTime();
                                System.out.println("departTime "+departTime);
                                String dest=leg.get(l).getDestination();
                                System.out.println("Destination "+dest);
                                String destTer= leg.get(l).getDestinationTerminal();
                                System.out.println("DestTer "+destTer);
                                String origin=leg.get(l).getOrigin();
                                System.out.println("origun "+origin);
                                String originTer=leg.get(l).getOriginTerminal();
                                System.out.println("OriginTer "+originTer);
                                int durationLeg= leg.get(l).getDuration();
                                System.out.println("durationleg "+durationLeg);
                                int mil= leg.get(l).getMileage();
                                System.out.println("Milleage "+mil);

                            }

                        }
                    }

                    //Pricing
                    List<PricingInfo> priceInfo= tripResults.get(i).getPricing();
                    for(int p=0; p<priceInfo.size(); p++){
                        String price= priceInfo.get(p).getSaleTotal();
                        System.out.println("Price "+price);
                    }

                }
              return;
            } catch (IOException e) {
              System.err.println(e.getMessage());
            } catch (Throwable t) {
              t.printStackTrace();
            }
            System.exit(1);

    }
}