java - 为火车预订系统设计一个类

Question

我是面向对象设计的新手，并且仍在学习它的过程中。
我为火车预订系统设计了一个类(class)，但我不确定如何对主要预订类(class)进行建模。

这就是我的设计的外观:

public class Station {
    private int stationID;
    private String stationName;

    // Getters and Setters
}

public class Train {
    private int trainID;
    private String trainName;
    private Map<Station, Double> trainStationsWithFares;

    public Train(int ID, String trainName, Station[] stations) {
    // Initialize ID and name and create a hashmap with all stations and
    // zero fare initially for all stations.
    ....
    trainStationsWithFares = new HashMap<Station, Double>();
    for(Station s : stations) trainStationsWithFares.put(s, new Double(0.0));
    }

    // Getters and Setters (including methods to add new stations with fares and
    // update fares of existing stations
}

public class Passenger {
    private String Name;
    private int id;
    private int age;
    private static final enum { Male, Female } gender; 
}

public class TicketDetails {
    private Train t;
    private Station from;
    private Station to;
    private Passenger passenger;

    // Getters and Setters
}

public class TrainTicket {
    private int ID;
    private TicketDetails ticketDetails;
    private Double fare;

    public TrainTicket(TicketDetails ticketDetails)
        throws InvalidTrainException, InvalidFromStationException,
            InvalidToStationException {
        ...
        calculateFare();
    }

    // Calculates fare based on Train and from and to Stations and taxes, etc.
    private void calculateFare() {
        this.fare = ...
    }
}

// Assuming card payment only for online reservation system for simplicity.
// Design can be modified and enhanced suitably.
public class PaymentDetails {
    private String cardNumber;
    private String cardExpirationMonth;
    private String cardExpirationYear;
    private String cardCVV;

    // Getters and Setters
}

我的 问题 : 我的预订类应该是这样的吗？
如果是这样，该类中的方法将如何访问其他类的对象，例如 TrainTicket , PaymentDetails ， ETC。？

public abstract class ReservationSystem {

    // Purchase train ticket by providing ticket details and payment details.
    public abstract TrainTicket purchaseTicket(TicketDetails ticketDetails,
        PaymentDetails paymentDetails);    

    // Cancel existing train ticket by providing ticket reference and payment details
    // for cancellation charges.
    public abstract boolean cancelTicket(TrainTicket tt, PaymentDetails details);

    // Modify existing train ticket by providing existing ticket reference,new ticket
    // details and payment details for any additional charge or modify charges.
    public abstract TrainTicket modifyTicket(TrainTicket existingTicket,
        TicketDetails newTicketDetails, PaymentDetails paymentDetails) {
    }
}

或者它应该看起来像这样:

public class ReservationSystem{
    private Map<trainId, Train> trains;   
    private Ticketdetails ticketdetails;
    private PaymentDetails paymentDetails;
    private TrainTicket tt;

    public vector<Train> getTrain(TicketDetails ticketdetails);
    public TrainTicket purchaseTicket(TicketDetails ticketDetails,
        PaymentDetails paymentDetails);    
    public boolean cancelTicket(TrainTicket tt, PaymentDetails details);
    public TrainTicket modifyTicket(TrainTicket existingTicket,
        TicketDetails newTicketDetails, PaymentDetails paymentDetails);
}

我想知道主 Reservation 类应该如何访问其他类的方法和成员。

提前致谢。

Answer 1

在前一种方法中，ReservationSystem类(class)是 abstract ，即它们不能被实例化，但应该被子类化以访问方法。如果您只有一种预订系统，那么为它创建抽象类是没有意义的。除此之外，我看不出您为 ReservationSystem 指定的 2 个备选方案之间有任何区别。类(class)。

来到第二个问题，

I want to know how should the main Reservation class access the methods and members of other classes

Train , Station和 TrainTicket类应该公开公共(public)访问器(getter 和 setter)和访问其数据的方法。由于您没有说明是否使用数据库来存储预订信息(如预订的门票等)，因此您需要将预订信息保存在 ReservationSystem 中。类本身，即应该有一个像 Map 这样的数据结构存储已预订的门票( Ticket.Id 最有可能是键)、已取消的门票等。调用 bookTicket()会将票添加到 Map和 cancelTicket()从 Map 中删除票证.

此外， ReservationSystem还需要维护与每个实例关联的有效火车和车站的列表。与系统的所有交互都是通过 ReservationSystem 的实例进行的。类(class)。