Help with progressing in my Assignment

[Kevin Thien]

I'm not looking for direct answers, but rather help in getting onto the right direction in regards to what I'm doing. My assignment is a text-based airline booking ticket. I'll past all the code given and that I've coded so far and explain my thought processes. There's a few things I'm totally confused about right now and would LOVE some help in understanding what I should be doing next.

import java.util.*;

public class Airline
{   public static void main(String[] args)
    {   
        new Airline();  
    }
    
    private Routes routes = new Routes();
    private Customers customers = new Customers();

    public Airline()
    {
        initialise();
    }
    
    public void initialise()
    {
        char choice = readChoice();
        while (!end(choice))
        {
            execute(choice);
            choice = readChoice();
        }
        System.exit(0);
    }
    
    public char readChoice()
    {
        System.out.print("Choice (a/b/c/s/?/x) : ");
        return In.nextChar();
    }
       
    private void execute(char choice)
    {   
        char aChoice = Character.toLowerCase(choice);
        switch (aChoice)
        {   
            case 'a': routes.show(); break;
            case 'b': customers.book(routes); break;
            case 'c': customers.show(); break;
            case 's': routes.showSchedule(); break;
            case 'x': break;
            case '?': menuExplanation(); break;
            default: System.out.println("Invalid choice. Enter '?' for an explanation of the menu."); break;
        }
    }
    
    private boolean end (char choice)
    {
        char aChoice = Character.toLowerCase(choice);
        return aChoice == 'x';
    }
    
    private void menuExplanation()
    {
        System.out.println("  A/a Show bookings by route");
        System.out.println("  B/b Book a trip");
        System.out.println("  C/c Show bookings by a customer");
        System.out.println("  S/s Show scheduele");
        System.out.println("  ? Show choices");
        System.out.println("  X/x Exit");
    }
}

import java.text.*;
import java.util.*;

public class Routes
{   private LinkedList<Route> routes = new LinkedList<Route>();
    private double cash;
    
    public void book(Flight flight)
    {   // the following line of ocde is wrong
        // it was added just to make the other code compile
        Route route = new Route();
    // this one line shows how the flight is passed on down the line
        route.book(flight);  }  // pass the flight on to class Route
    // you need more code in this method than just this one line

    public Route route(String source, String destination)
    {   
        return null;    
    }   // lookup
        
    public void show()
    {
        
    }
        
   public void showSchedule()
   {
        System.out.println("  Beijing to Paris: 2 5 6 9");
        System.out.println("  Beijing to Woy Woy: 2 4 8");
        System.out.println("  Paris to Beijing: 2 5 6 9");
        System.out.println("  Paris to Woy Woy 1 3 5");
        System.out.println("  Woy Woy to Beijing: 2 4 8");
        System.out.println("  Woy Woy to Paris: 1 3 5");
   }
}

import java.util.*;

public class Route implements Comparable<Route>
{   
    private String source;
    private String destination;
    private int[] times;
    private double baseCost;
    private final double fuel = 10;
    private final double air = 25;
    private final double seat = 12.34;
    private LinkedList<Day> days = new LinkedList<Day>();
   
    public void book(Flight flight)
    {   // add this route to the flight
        flight.add(this);
        // get the day (not shown) and pass on the flight
        // you need more code in this method than just these two lines
        // these two lines show how you add to a flight and then pass it on
        Day day = day(0); // this line of code is wrong; replace it
        day.book(flight);  }
        
    private Day day(int date)
    {   return null;    }   // lookup code goes here
    
    public int compareTo(Route other)
    {   // the following line of code is wrong; replace it
        return 0;   }
}

import java.util.*;

public class Day implements Comparable<Day>
{   private int date;
    private LinkedList<Pod> pods = new LinkedList<Pod>();
    
    public void book(Flight flight)
    {    }
        
    private Pod nextPod(int time)
    {   return null;    }   // tweaked lookup code goes here
        
    public int compareTo(Day other)
    {   return 0; } // this code is wrong; replace it
    
    public int date()
    {   return date;    }
}

import java.util.*;

public class Pod
{   private int time;
    private LinkedList<Flight> flights = new LinkedList<Flight>();
}

import java.util.*;

public class Customers
{   private LinkedList<Customer> customers = new LinkedList<Customer>();

    public void book(Routes routes)
    {   
        Trip trip = new Trip(routes);
        // the followingl ine of code is there just to make the method compile
        // you need to change it; it is wrong
        Customer customer = customer("er");
        // I just wanted to show you how a trip is added to the customer
        customer.add(trip); 
    }
        // you need more code in this method than just these three lines
    
    public Customer customer(String name)
    {   
        return null;    
    }   // lookup code goes here
  
    public void show()
    {   
        System.out.print(toString());  
    }
        
    public String toString()
    {   
        return "hi";   
    }
}

import java.util.*;

public class Customer
{   private String name;
    private LinkedList<Trip> trips = new LinkedList<Trip>();
    
    public void add(Trip trip)
    {   trips.add(trip);    }
}

import java.util.*;

public class Trip
{   private LinkedList<Flight> flights = new LinkedList<Flight>();
    private double cost;
    
    public Trip(Routes routes)
    {   }   // menu goes here
        
    private void book(Routes routes)
    {   Flight flight = new Flight();
        // pass the flight down the line, adding detail as you go
        routes.book(flight);
        // add the flight to this trip
        flights.add(flight);    }
}

public class Flight
{   private Route route;
    private Day day;
    private Pod pod;
    private int seat;
    
    public Flight()
    {   }
    
    // add the route to this flight
    public void add(Route route)
    {   this.route = route; }
}

import java.util.*;

public class In
{   private static Scanner in = new Scanner(System.in);
    
    public static String nextLine()
    {   return in.nextLine(); }
    
    public static char nextChar()
    {   return in.nextLine().charAt(0); }
    
    public static int nextInt()
    {   int i = in.nextInt();
        in.nextLine();
        return i;   }

    public static double nextDouble()
    {   double d = in.nextDouble();
        in.nextLine();
        return d;   }
}

I've coded the beginning menu which is fine. The next part I was going to code was the main booking option. The way our teacher has set out this model code is that we're suppose to pass attributes down from route > day > pod and the route itself is passed to the customer and it's flight. We were told to create all the possible flight routes in constructor of the Day class (Why, this I don't really understand).

The current part I'm stuck on is implementing the choice "b" to book. Example IO given to us is along the lines of:

Choice(a/b/c/s/?/x): b
  Single, return, or on (s/r/o/x): r
  Source: Woy Woy
  Destination: Paris
  Day: 2
  Time: 3
      OA flight 2.3.2: Woy Woy to Paris at $97.34
      OA flight 3.3.1: Paris to Woy Woy at $97.34
  Single, return, or on (s/r/o/x): x
  Name: fred

While getting the S.o.p is simple, I'm unsure of how I'm suppose to be passing these attributes down as the switch code for booking is:

case 'b': customers.book(routes); break;

I don't really understanding why the base code we were given to work off of passes routes down as the variable when we want to begin booking.

[Steve Luke]

Consider this: a customer gets to this screen and for the source types London and the destination types Cairo. Is this valid? How do you know? More importantly, how would the method know?

[Winston Gutkowski]

Kevin Thien wrote:I don't really understanding why the base code we were given to work off of passes routes down as the variable when we want to begin booking.

I have to admit, I share your confusion slightly; but your teacher may be making a distinction between the booking process and an actual ticket.

Sometimes it's worth turning OFF your computer and stepping back from the business of coding to analyse the components you're dealing with. And make your notes (or diagrams) in English.

If I see it right, you might end up with definitions like this:
1. Route - A point-to-point transfer operated by an Airline.
2. Airline - A carrier company that operates Flights that cover designated Routes.
3. Flight - A scheduled transfer over a Route in one direction, operated by a specific Airline.
4. Trip - An itinerary of Flights required to complete a journey.
...

Hopefully you get the idea. Going through that sort of process may help you to follow what's being asked of you - and maybe ask questions about the rest. Unless your teacher is a complete duffus, there's absolutely nothing wrong with questioning a design.

Personally, I don't like the idea of a Route containing a book() method either. I'd have put it in the Flight class and had it return a Ticket. But there may well be a need for a generalized search of a Route when you're trying to book, for Flights that go on a particular day for example; and maybe that's what the method is intended to do (if so, I think I'd have called it flights() though).

Sounds like a good exercise though, because now you're starting to get a feel for what programming is really about.

Winston

[K. Tsang]

Winston is correct, first you need to understand what the purpose is for each class or source file. Then connect them using flow chart finding the logic of the booking process. From there you will able to start coding.

Good luck

[Kevin Thien]

We were actually given a design flow for his model solution which actually gave me the most confusion. The client chart flow was:

Airline has Routes and Customers. Routes have route. Route has Days. Days have Pods. Customers have Customer. Customer has Trip. Trip has routes and a Flight. Flight has a route.

2. Make a booking
This is a standard lookup framework, with two tweaks:
* Create each day as needed
Add all the (empty) flights in the Day constructor; only show booked flights
A Route function finds or creates the desired day
class Route
{ private Day aDay(int day)
{ if this day exists, return it
          else return a new day }
* Pass the routes down to the customer; they are used and not stored
class Airline
{ private void execute(char choice)
{ …
case ‘b’: customers.book(routes);
class Customers
{ public void book(Routes routes)
{ Trip trip = new Trip(routes);
…
customer.add(trip); }
class Trip
{ public Trip(Routes routes)
{ read customer choice
book flights as needed }

What I don't really get is why it's passing down route as a variable. I can code the S.o.p and corresponding variable input, S.o.p("Destination"); destination = In.nextLine(); as well as the validity checks.

[Steve Luke]

The first question to answer is: What does Routes do? It has 'Route' objects, but what is the purpose of Routes, what action does it do, or what data is it supposed to hold?

The next question is: Why does the customers.book() method need that/those actions or data.

[Winston Gutkowski]

Kevin Thien wrote:Route has Days. Days have Pods...Trip has routes and a Flight.

I have to admit that these 3 are a bit odd.

First: What is a Day? If it's a "calendar day" or a "day of the week" then it's likely to be affected by timezone (and BTW, most airlines work in Zulu time (GMT) - at least the one I worked for did). If it's simply a 24-hour period starting from some arbitrary point, that seems a lot more reasonable; but then the key doesn't make much sense.

Second: What is a Pod? Is it some acronym like 'Point of Departure'?

Third: I can see why a Trip might equate to a set of Routes, but then why only a single Flight?

Seems to me like you need to get the specifics of this stuff sorted out in your own mind; and I suspect the only thing that will help you with that is a Vulcan mind-meld with your teacher.

Winston

[Steve Luke]

Winston Gutkowski wrote:Third: I can see why a Trip might equate to a set of Routes, but then why only a single Flight?

The Trip is not a collection of Routes, it is a collection of Flights. The Routes object is passed in to Trip for a purpose, but you will notice there is no place to store it, and you will notice it is passed in again in the only other method in Trip, so the intent is not to store Routes in Trip.

Routes consists of a list of Route objects. It has methods to look up a route based on source and destination, but also note there is no method used to add a Route to the collection. I think this is enough to deduce what Routes is intended to be (and from that why you need it when trying to book a flight).

[Winston Gutkowski]

Steve Luke wrote:The Trip is not a collection of Routes, it is a collection of Flights. The Routes object is passed in to Trip for a purpose, but you will notice there is no place to store it, and you will notice it is passed in again in the only other method in Trip, so the intent is not to store Routes in Trip.

Quite right. I was going by OP's description instead of looking at the classes. I still reckon this Day and Pod business is rather confusing though, but maybe they're explained better in the requirements doc.

I also question the logic of having a Trip made up of Flights, because that suggests to me that it's the result of a booking process. If I walk into a Travel agent, I will presumably already have a Trip planned; what I won't have is any knowledge about Routes or Flights or Pods.

To me, the result of a booking process is a Ticket (or Tickets) ... and, no doubt, a Payment.

Winston

[Kevin Thien]

Been a while since I've posted back but I've got most of my things to work. Currently I'm trying to get a check done for the time a user inputs and validating with my array of times. Currently I'm getting my array to be null and I can't figure out why.

public void book(Flight flight)
    {  
        source = getSource();
        destination = getDestination();
        System.out.print(source + destination);
        times = initialiseTimes(source, destination);
        System.out.print(Arrays.toString(times));
        flight.add(this);
        Day day = new Day(readDay());
        int time = getTime();
        /*for (int i = 0; i <=4; i++)
        {           
            if (time == times[i])
            {
                day.book(flight);
            }
            else
            {
                System.out.print("    Not available");
            }
        }*/
    }

    public int[] initialiseTimes(String source, String destination)
    {
        this.source = source.toLowerCase();
        this.destination = destination.toLowerCase();        
        if (source.equals("beijing") && destination.equals("paris"))
        {    times = new int[]{2, 5, 6, 9};   }
        else if (source.equals("beijing") && destination.equals("woy woy"))
        {    times = new int[]{2, 4, 8};    }
        else if (source.equals("paris") && destination.equals("beijing"))
        {    times = new int[]{2, 5, 6, 9};    }
        else if (source.equals("paris") && destination.equals("woy woy"))
        {    times = new int[]{1, 3, 5};    }
        else if (source.equals("woy woy") && destination.equals("beijing"))
        {    times = new int[]{2, 4, 8};    }
        else if (source.equals("woy woy") && destination.equals("paris"))
        {    times = new int[]{1, 3, 5};    }
        return times;  
    }        

The source and destination are definitely being picked up cause I can see them in my S.o.P debug, but they won't initialise my times array properly. I'm racking my brain on this right now and I can't figure it out.

*EDIT I'm an idiot with strings. Fixed it with a stupid way.

public int[] initialiseTimes(String source, String destination)
    {
        String sourceL = source.toLowerCase();
        String destinationL = destination.toLowerCase();
        System.out.print(sourceL + destinationL);
        if (sourceL.equals("beijing") && destinationL.equals("paris"))
        {    times = new int[]{2, 5, 6, 9};   }
        else if (sourceL.equals("beijing") && destinationL.equals("woy woy"))
        {    times = new int[]{2, 4, 8};    }
        else if (sourceL.equals("paris") && destinationL.equals("beijing"))
        {    times = new int[]{2, 5, 6, 9};    }
        else if (sourceL.equals("paris") && destinationL.equals("woy woy"))
        {    times = new int[]{1, 3, 5};    }
        else if (sourceL.equals("woy woy") && destinationL.equals("beijing"))
        {    times = new int[]{2, 4, 8};    }
        else if (sourceL.equals("woy woy") && destinationL.equals("paris"))
        {    times = new int[]{1, 3, 5};    }
        return times;  
    }

Now my issue is with

for (int i = 0; i <=4; i++)
        {           
            if (time == times[i])
            {
                day.book(flight);
            }
            else
            {
                System.out.print("    Not available");
            }
        }

How do I make it not print "Not available" for each instance of the array it checks?