serialization and deserialization

How do you go about serialization and deserialization of the Airplane Class ?

We are still not doing objects in class which is why I am asking this question ,
:JIM YOU THERE :-):

From the problem description, several classes jumped out at me: Airplane, SeatingClass, Seat, and Passenger. Pretty much everything else seemed to be attributes of these four classes.

Airplane knows it two seating classes and provides upper level assistance for the assignment of seats and printing of the passenger manifest.

SeatingClass creates and manages Seats. It can find an unassigned seat of the supplied seating preference      and collaborates in printing the manifest.

Seat knows its occupant of Passenger. It provides a reserve() method for establishing this relationship along with the price charged for the booking. The date of the booking is assumed to be the current date. It collaborates in printing the manifest by providing a toString() implementation appropriate to the task.

Passenger is the occupant. It knows first and last name and provides a toString() method that can be used for adding this detail to the manifest.

These four classes with initial implementation appear below. The final class is the TicketAgent which is where most of your implementation remains to be done. The text prompts, gathering and parsing user input, and acting upon the input need to be added. Object serialization and deserialization becomes fairly simple because all the objects are related to Airplane:

Airplane -- has 2 -- SeatingClass -- has many -- Seat -- has 1 -- Passenger

All the classes implement Serializable so all you have to do is serialize Airplane to a file and you're done. Serialization takes care of traversing the network of objects and getting them all written. I think Date and String are the only jdk objects I used and these both implement Serializable. Deserialize from the file when the program starts and you can work with the objects in memory as you please.

Note that creating a new Airplane creates all the necessary objects except the Passenger objects. These need to be created just prior to reserving a seat as shown in TicketAgent.reserveSeat().

One bell I stubbed in would allow for working with multiple airplanes as chosen by a command line argument which names the file that contains the serialized object Airplane object. You can choose not to implement this.

I hope that I have neither provided too much assistance nor too little. I think that the code is mostly self-explanatory. All the code compiles as is and basically runs -- although the only thing it does is print a manifest of unoccupied seats.

Good luck.
Jim Cakalic

---------- Airplane.java ----------
import java.io.Serializable;

public class Airplane implements Serializable {
    private SeatingClass firstClass;
    private SeatingClass economyClass;

    public Airplane() {
        // create seating classes of fixed size
        economyClass = new SeatingClass(10, 6);
        firstClass = new SeatingClass(5, 4);
    }

    public Seat assignSeat(int seatingClass, int preference) {
        if (seatingClass == SeatingClass.FIRST) {
            return firstClass.assignSeat(preference);
        } else if (seatingClass == SeatingClass.ECONOMY) {
            return economyClass.assignSeat(preference);
        } else {
            return null;
        }
    }

    public void printManifest() {
        System.out.println("First class:");
        firstClass.printManifest();
        System.out.println("Economy class:");
        economyClass.printManifest();
    }

}

---------- SeatingClass.java ----------
import java.io.Serializable;

public class SeatingClass implements Serializable {
    public static final int FIRST = 1;
    public static final int ECONOMY = 2;

    private Seat[][] seats;

    public SeatingClass(int rows, int seatsPerRow) {
        // Technically, we should require seatsPerRow to be even.
        // Assume that it is for this assignment
        seats = new Seat[rows][seatsPerRow];
        for (int i = 0; i < rows; ++i) {
            seats[i][0] = new Seat(Seat.WINDOW);
            for (int j = 1; j < seatsPerRow - 1; ++j) {
                boolean aisle = (j == (seatsPerRow / 2 - 1) || j == (seatsPerRow / 2 + 1));
                seats[i][j] = new Seat(aisle ? Seat.AISLE : Seat.CENTER);
            }
            seats[i][seatsPerRow - 1] = new Seat(Seat.WINDOW);
        }
    }

    public Seat assignSeat(int preference) {
        for (int i = 0; i < seats.length; ++i) {
            for (int j = 0; j < seats[0].length; ++j) {
                Seat seat = seats[i][j];
                if (seat.isPosition(preference) && seat.isReserved() == false) {
                    // Found an unoccupied seat matching the stated preference
                    return seats[i][j];
                }
            }
        }
        // No qualifying unoccupied seats found
        return null;
    }

    public void printManifest() {
        for (int i = 0; i < seats.length; ++i) {
            for (int j = 0; j < seats[0].length; ++j) {
                Seat seat = seats[i][j];
                // This needs a lot of work!!
                System.out.println(i + "-" + j + ": " + seat.toString());
            }
        }
    }

}

---------- Seat.java ----------
import java.io.Serializable;
import java.util.Date;

public class Seat implements Serializable {
    // Seating positions
    public final static int WINDOW = 1;
    public final static int CENTER = 2;
    public final static int AISLE = 3;

    private Passenger passenger;
    private Date bookingDate;
    private float ticketPrice;
    private int position;

    public Seat(int position) {
        this.position = position;
    }

    public boolean isReserved() {
        return passenger != null;
    }

    public void reserve(Passenger passenger, float price) {
        this.passenger = passenger;
        ticketPrice = price;
        bookingDate = new Date();
    }

    public Passenger getPassenger() {
        return passenger;
    }

    public Date getBookingDate() {
        return bookingDate;
    }

    public float getTicketPrice() {
        return ticketPrice;
    }

    public boolean isPosition(int preference) {
        return position == preference;
    }

    public String toString() {
        if (isReserved() == false) {
            return "unoccupied";
        }
        return passenger.toString();
    }
}

---------- Passenger.java ----------
import java.io.Serializable;

public class Passenger implements Serializable {
    private String lastName;
    private String firstName;

    public Passenger(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public String toString() {
        return lastName + ", " + firstName;
    }

}

---------- TicketAgent.java  ----------
public class TicketAgent {
    Airplane airplane;

    public TicketAgent() {
        airplane = new Airplane();
    }

    public void selectFlight(String[] args) {
        // Deserialize airplane from serialized file
        // Maybe take name of file from args?
        // Sets the airplane instance variable
    }

    public void interact() {
        // Loop asking for next choice: reserve seat, print manifest, quit
        // Method doesn't return until quit is chosen
        System.out.println("What do you want to do today?");
        printManifest();
    }

    public void updateFlight(String[] args) {
        // Serialize airplane to file
        // Maybe take name of file from args?
    }

    public void reserveSeat() {
        int seatingClass = SeatingClass.FIRST;
        int seatingPreference = Seat.AISLE;

        // Ask for class and seating preference

        Seat assignment = airplane.assignSeat(seatingClass, seatingPreference);
        if (assignment == null) {
            // apologize because no seats matching the preference
        } else {
            // ask for passenger name
            // set the price for the seat?
            // reserve this seat
            Passenger passenger = new Passenger("John", "Doe");
            float price = 1000.0f;
            assignment.reserve(passenger, price);
        }
    }

    public void printManifest() {
        airplane.printManifest();
    }

    public static void main(String[] args) {
        TicketAgent agent = new TicketAgent();
        agent.selectFlight(args);
        agent.interact();
        agent.updateFlight(args);
    }
}
---------- end ----------