如何为订单类中的每个职位设置折扣

Question

我有一个程序，我在position类中为每个职位设定价格和数量。在订单类别中，我计算产品并给予折扣。我有一种计算折扣的方法，我计算所有产品的总折扣。每个职位我都想打折扣，但我不知道怎么打。我问一个朋友一些建议。

 package programming.com.pl;

public class Position  {

    private String name;
    private double price = 0;
    private int quantity = 0;


    public Position(String name, double price, int quantity){
        this.name = name;
        this.price = price;
        this.quantity = quantity;
    }

    public double getPrice() {
        return price;
    }

    public int getQuantity() {
        return quantity;
    }

    public String toString(){
        String str = String.format("%4s,%4s zł,%2s szt.", name,price,quantity);
        return  str;
    }
}

package programming.com.pl;

import java.util.ArrayList;

public class Order {
    final private ArrayList<Position> positions = new ArrayList<>();



    private double calculateProduct() {
        double sum = 0;
        for (Position position : positions) {
            sum = position.getPrice();
        }
        return sum;
    }

    double sumOrder() {
        double sum = 0;
        for (Position x : positions) {
            sum += calculateProduct();
        }
        return sum;
    }


    void addPosition(Position p) {
        positions.add(p);
    }

    void deletePosition(int index) {
        positions.remove(index);
    }




    double calculateDiscount() {
        double salePrice = 0;
        for (Position position : positions) {
            if (position.getQuantity() >= 5 && position.getQuantity() <= 10) {
                salePrice = calculateProduct() - (calculateProduct() * 0.05);
            } else if (position.getQuantity() <= 10 && position.getQuantity() <= 20) {
                salePrice = calculateProduct() - (calculateProduct() * 0.1);
            } else {
                salePrice = calculateProduct() - (calculateProduct() * 0.15);
            }

        }

        return salePrice;
    }
    public String toString() {
        StringBuilder sb = new StringBuilder("Order is: \n");

        for (Position p : positions) {
            sb.append(p).append("\n");
        }
        sb.append("Order sum is: ").append(sumOrder()).append("\n");
        sb.append("Discount is: ").append(calculateDiscount());
        return sb.toString();
    }
}

Answer 1

不太确定你在问什么。您是否试图根据数量更新销售价格？如果是这样，只需在相关的if循环中更新它，例如，如果5到10之间的数量适用5%的折扣，那么：

salePrice = (salePrice = calculateProduct() - (calculateProduct() * 0.05)) * 0.95

如果折扣适用于其他地方，则只需为每个数量案例设置一个var：

if (position.getQuantity() >= 5 && position.getQuantity() <= 10) {
     salePrice = calculateProduct() - (calculateProduct() * 0.05);
     discount = 0.95
}

在必要的情况下，将折扣乘以价格。