java - 如何调用一个类，以便方法根据该类中的变量执行特定操作

Question

我对这个标题深表歉意，我愿意接受建议，将其重命名为更清晰的名称

我的问题是我有一个任务，其中有 3 张单独的卡片代表特定商店内的不同成员(member)状态。有基本卡、银卡和金卡。根据卡的不同，年底会向客户发放不同的优惠券。现在我在主类中创建优惠券方法。我一直在尝试让该方法适用于每张卡的不同操作方式。

本质上，该方法会查看客户拥有什么卡并应用适当的折扣，例如，如果客户使用基本卡并且余额(总支出)超过 2000 美元，则优惠券为 3%

下面是我目前拥有的(请注意，我并不担心创建 3 个卡类，我只想让其中一个工作)

    public class storeCard {

        public static void main(String[] args) {

            cardDetails detailsObject1 = new cardDetails(0001, "Adam Gong", 7000);
            Date date = new Date(04, 8, 2019);
            storeCard store = new storeCard();
            basicCard card = new basicCard();

            System.out.println("***** Customer Details ******");
            System.out.println("Customers name: " + detailsObject1.getName());
            System.out.println("Customers ID: " + detailsObject1.getID());
            System.out.println("Customers balance: " + detailsObject1.getBalance());
            System.out.println("Created Date: " + date.getDay() + "/" + date.getMonth() + "/" + date.getYear());
            Address addressObject1 = new Address(63, "Boyd Street", "Eagle Vale", "Campbelltown", "NSW", 2558);

        }

        public void calCoupon(double balance) {

            if(balance < 2000);
            System.out.println("Coupon is 2%");


        }

    }

    import java.util.*;

class cardDetails {

    private int ID;
    private String name;
    private double balance;

    public cardDetails(int ID, String name, double balance) {

        this.ID = ID;
        this.name = name;
        this.balance = balance;

    }

    public int getID() {

        return this.ID;
    }

    public void setID(int customerID) {

        this.ID = customerID;

    }

    public String getName() {
        return this.name;
    }

    public void setName(String customerName) {

        this.name = customerName;
    }

    public double getBalance() {
        return this.balance;
    }

    public void setBalance() {
        this.balance = balance;
    }

}

import java.util.*;

class Date {

    private int day, month, year;

    public Date(int day, int month, int year) {
        this.day = day;
        this.month = month;
        this.year = year;
    }

    public int getDay() {

        return this.day;
    }

    public void seDay(int Day) {

        this.day = day;

    }

    public int getMonth() {
        return this.month;
    }

    public void setMonth(int Month) {

        this.month = Month;
    }

    public int getYear() {
        return this.year;
    }

    public void setYear(int Year) {
        this.year = Year;
    }

    public String toString() {
        return new String("date=" + day + ",month=" + month + ",year=" + year);

    }
}

  import java.util.*;

class Address {

    private int streetNumber;
    private String streetName;
    private String suburb;
    private String city;
    private String state;
    private int postcode;

    public Address(int streetNumber, String streetName, String suburb, String city, String state, int postcode) {
        this.streetNumber = streetNumber;
        this.streetName = streetName;
        this.suburb = suburb;
        this.city = city;
        this.state = state;
        this.postcode = postcode;

        System.out.println("Customers Address: " + this);

    }

    public String toString() {
        return new String( streetNumber + " " +streetName + " " + suburb + " " + city + " " + state + " " + postcode);

    }
}

class basicCard { 
    final double discount = 0.03;
    double annuelFee = 10;
}

Answer 1

尚不完全清楚这是否是您所要求的，但您可能希望为卡的功能创建一个接口(interface)，并让具体的卡实现它。

interface Card {
    double getDiscount(double moneySpent);
}

class BasicCard implements Card {
    public double getDiscount(double spent) {
        return spent < 2000d ? 0 : 3;
    }
}

class SilverCard implements Card {
    public double getDiscount(double spent) {
        return spent < 2000d ? 1 : 5;
    }
}

class PremiumCard implements Card {
    public double getDiscount(double spent) {
        return spent < 2000d ? 3 : 8;
    }
}

那么总共花费的钱是

double baseAmount = 2500; // for example
double total = baseAmount - (customer.getCard().getDiscount(baseAmount) * baseAmount);

您可能并不真正需要子类，但可以使用工厂方法。

class Cards {
    public static Card basicCard() {
        return amount -> amount < 2000d ? 0 : 3;
    }
    public static Card silverCard() {
        return amount -> amount < 2000d ? 1 : 5;
    }
    public static Card basicCard() {
        return amount -> amount < 2000d ? 5 : 8;
    }
}