Menu
I'm writing a program that displays flight information as seen bellow:
package d.airlineData.engine;
import java.time.Duration;
import java.time.LocalTime;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map.Entry;
import a.airlineData.exceptions.NoFlightsException;
import c.airlineData.exceptions.NoAirportException;
import d.airlineData.graph.Airport;
import d.airlineData.graph.Flight;
import d.airlineData.graph.FlightGraph;
public class FlightGrapher {
private FlightGraph fg;
public FlightGrapher() throws NoFlightsException {
throw new NoFlightsException();
}
public FlightGrapher(ArrayList<Flight> flights) throws NoFlightsException {
fg = new FlightGraph();
for(Flight flight: flights) {
fg.addAirport(flight.getAirportA());
fg.addAirport(flight.getAirportB());
try {
fg.addFlight(flight);
} catch (NoAirportException e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
}
}
public void printAll() {
HashSet<Airport> airports = fg.getAirports();
for(Airport airport : airports) {
System.out.println(airport + ":");
try {
Iterator<Flight> it = fg.getFlightsFor(airport);
while(it.hasNext()) {
System.out.println("\t" + it.next());
System.out.println();
}
} catch (NoAirportException e) {
System.err.println(e.getMessage() + " while attempting to get flights for " + airport);
e.printStackTrace();
}
}
}
public void printItinerary(Airport airportA, Airport airportB) {
System.out.println("Leg\tLeave\t\tAt\tOn\tArrive\tAt");
printItinerary(airportA,airportB, 1, 0.0, Duration.ofHours(0));
}
private void printItinerary(Airport airportA, Airport airportB, int leg, double totalPrice, Duration totalDuration) {
Iterator<Flight> aFlights = airportA.getOutgoingFlights();
System.err.println("Enters method printItinerary");
System.err.println("airportA " + airportA);
System.err.println("airportB " + airportB);
System.err.println("leg " + leg);
System.err.println("total price " + totalPrice);
System.err.println("Duration " + totalDuration.toMinutes() + "mins");
System.err.println();
while(aFlights.hasNext()) {
Flight currentFlight = aFlights.next();
System.err.println("Enters while of printItinerary currentFlight: ");
System.err.println(currentFlight);
if(currentFlight.getAirportB().equals(airportB)) {
System.out.println(leg + "\t" +
currentFlight.getAirportA() + "\t" +
currentFlight.getDepartureTime() + "\t" +
currentFlight.getFlightNumber() + "\t" +
currentFlight.getAirportB() + "\t" +
currentFlight.getArrivalTime());
System.out.println();
System.out.println("Total journey costs\t= £" + (currentFlight.getPrice() + totalPrice));
System.out.println("Total time in air\t= " + (currentFlight.getFlightDuration().plus(totalDuration)));
return;
}else {
System.err.println("enters else " + "currentFlight " + currentFlight.getAirportB() + " airport B " + airportB );
System.err.println();
if(hasAPath(currentFlight.getAirportB(), airportB)) {
System.out.println(leg + "\t" +
currentFlight.getAirportA() + "\t" +
currentFlight.getDepartureTime() + "\t" +
currentFlight.getFlightNumber() + "\t" +
currentFlight.getAirportB() + "\t" +
currentFlight.getArrivalTime());
printItinerary(currentFlight.getAirportB(), airportB, leg + 1,
(currentFlight.getPrice() + totalPrice),
(currentFlight.getFlightDuration().plus(totalDuration)));
}
}
}
}
private boolean hasAPath(Airport airportA, Airport airportB) {
System.err.println("Enters hasAPath with airportA " + airportA + " airportB " + airportB);
Iterator<Flight> aFlights = airportA.getOutgoingFlights();
while(aFlights.hasNext()) {
Flight currentFlight = aFlights.next();
System.err.println("Enters while of hasAPath currentFlight: ");
System.err.println(currentFlight);
if(currentFlight.getAirportB().equals(airportB)) {
System.err.println("returns true for airportA " + airportA + " airportB " + airportB );
return true;
}else {
System.err.println("Calls hasAPath with airportA " + currentFlight.getAirportB() + " airportB " + airportB);
return hasAPath(currentFlight.getAirportB(), airportB);
}
}
System.err.println("returns false for airportA " + airportA + " airportB " + airportB );
return false;
}
public static void main(String[] args) {
ArrayList<Flight> flights = new ArrayList<>();
HashMap<String, Airport> airports = new HashMap<>();
airports.put("Edinburgh", new Airport("Edinburgh"));
airports.put("Heathrow", new Airport("Heathrow"));
airports.put("Amsterdam", new Airport("Amsterdam"));
airports.put("Boston", new Airport("Boston"));
airports.put("Montreal", new Airport("Montreal"));
airports.put("Chicago", new Airport("Chicago"));
airports.put("Toronto", new Airport("Toronto"));
airports.put("New Delhi", new Airport("New Delhi"));
airports.put("Shanghai", new Airport("Shanghai"));
airports.put("Hong Kong", new Airport("Hong Kong"));
flights.add(new Flight(airports.get("Edinburgh"),airports.get("Heathrow"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 110.0));
flights.add(new Flight(airports.get("Heathrow"),airports.get("Amsterdam"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 100.0));
flights.add(new Flight(airports.get("Heathrow"),airports.get("Boston"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 230.0));
flights.add(new Flight(airports.get("Boston"),airports.get("Chicago"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 150.0));
flights.add(new Flight(airports.get("Boston"),airports.get("Montreal"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 100.0));
flights.add(new Flight(airports.get("Montreal"),airports.get("Toronto"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 90.0));
flights.add(new Flight(airports.get("Edinburgh"),airports.get("Chicago"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 560.0));
flights.add(new Flight(airports.get("New Delhi"),airports.get("Shanghai"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 430.0));
flights.add(new Flight(airports.get("Shanghai"),airports.get("Hong Kong"),
"B7982",LocalTime.of(22,10),LocalTime.of(23,15), 230.0));
Iterator<Entry<String,Airport>> airportIt = airports.entrySet().iterator();
while(airportIt.hasNext()) {
Entry<String, Airport> pair = airportIt.next();
Airport airport = pair.getValue();
for(Flight flight: flights) {
if(flight.getAirportA().equals(airport)) {
airport.addOutgoingFlight(flight);
}
}
}
try {
FlightGrapher fg = new FlightGrapher(flights);
//fg.printAll();
fg.printItinerary(airports.get("Edinburgh"), airports.get("Toronto")); // steps into this method
} catch (NoFlightsException e) {
System.err.println(e.getMessage() + " when trying to make a flight between a nonexistant airport");
e.printStackTrace();
}
}
}
The problem I have is when using the method:
printItinerary(Airport airportA, Airport airportB, int leg, double totalPrice, Duration totalDuration)
It doesn't execute for some reason when normally running, but when I step though the program using the debugger everything executes fine and I get a meaningful output (not very well formatted, but something I can work with), why is this happening?
The output should look like this :
Leg Leave At On Arrive At
1 Edinburgh 10:30 BA345 Heathrow 11:30
2 Heathrow 14:00 BA657 Boston 15:30
3 Boston 18:00 AA652 Montreal 19:30
4 Montreal 22:00 AA216 Toronto 23:30
Total Journey Cost = £530
Total Time in the Air = 4 hrs 20 min
I get this when I just run it normally:
Leg Leave At On Arrive At
and this when I step though (or run on debug):
Leg Leave At On Arrive At
1 Edinburgh 22:10 B7982 Heathrow 23:15
2 Heathrow 22:10 B7982 Boston 23:15
3 Boston 22:10 B7982 Montreal 23:15
4 Montreal 22:10 B7982 Toronto 23:15
Total journey costs = £530.0
Total time in air = PT4H20M
the stepping though part is what I want to be outputted (I'll work on the formatting later)
eddit: I've added a bunch of outputs on the error stream and here is the output when I run it... for some reason it stops in the "hasAPath" method:
Leg Leave At On Arrive At
Enters method printItinerary
airportA Edinburgh
airportB Toronto
leg 1
total price 0.0
Duration 0mins
Enters while of printItinerary currentFlight:
Flight between Edinburgh & Chicago:
For: £560.0
Flight Number: B7982
Leaves at: 22:10
Arrives at: 23:15
Duration: 1hr 5min
enters else currentFlight Chicago airport B Toronto
Enters hasAPath with airportA Chicago airportB Toronto
returns false for airportA Chicago airportB Toronto
Enters while of printItinerary currentFlight:
Flight between Edinburgh & Heathrow:
For: £110.0
Flight Number: B7982
Leaves at: 22:10
Arrives at: 23:15
Duration: 1hr 5min
enters else currentFlight Heathrow airport B Toronto
Enters hasAPath with airportA Heathrow airportB Toronto
Enters while of hasAPath currentFlight:
Flight between Heathrow & Amsterdam:
For: £100.0
Flight Number: B7982
Leaves at: 22:10
Arrives at: 23:15
Duration: 1hr 5min
Calls hasAPath with airportA Amsterdam airportB Toronto
Enters hasAPath with airportA Amsterdam airportB Toronto
returns false for airportA Amsterdam airportB Toronto
at this point it should return out and then check hasAPath for the next flight which would be Boston and Toronto, which would then check all Bostons outgoign flights to see if their airports have a connection with toronto... and so on
601
Problem solved. The answer was that when you run in debug it runs though all of the possibilities even if you return the answer, this is why it evaluated to true and worked, I changed the has a path method from this :
private boolean hasAPath(Airport airportA, Airport airportB) {
Iterator<Flight> aFlights = airportA.getOutgoingFlights();
while(aFlights.hasNext()) {
Flight currentFlight = aFlights.next();
if(currentFlight.getAirportB().equals(airportB)) {
return true;
}else {
return hasAPath(currentFlight.getAirportB(), airportB);
}
}
return false;
}
To this:
private boolean hasAPath(Airport airportA, Airport airportB) {
Iterator<Flight> aFlights = airportA.getOutgoingFlights();
while(aFlights.hasNext()) {
Flight currentFlight = aFlights.next();
if(currentFlight.getAirportB().equals(airportB)) {
return true;
}else {
if(hasAPath(currentFlight.getAirportB(), airportB)) {
return true;
}else {
continue;
}
}
}
return false;
}
If anyone else is looking this problem then I suggest placing outputs to the console at each block of your code and following through what is happening, the execution model in debug mode must be different from that in normal running.
80
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With