Question

我试图制作程序，以便dicountPrice等于相应的if语句。我不太确定我的if声明或者我在课堂上遗漏了什么。我已经尝试过超级购买和购买这些商品。到目前为止，我已经难倒了。

示例输出：

名称：白雪公主
地址：111矮人巷
电话：555-0000
客户编号：200-A010
客户类型：首选
总购买量：2566.0
总欠款：2566.0
总折扣百分比：0.0
总欠款折扣：2566.0

但我需要折扣百分比为10

TIA

public class Customer extends Person {
protected String customerNumber, customerType;
protected double purchases;

Customer(){

    super(DEFAULT_VALUE,DEFAULT_VALUE,DEFAULT_VALUE);
    setCustomerType(DEFAULT_VALUE);
    setPurchases(0.0);

}

Customer(String name, String address, String phone, String cusNum, String cusType, double purch){
    super (name,address, phone);
    customerNumber = cusNum;
    customerType = cusType;
    purchases = purch;
}
public void setCustomerNumber(String custNum){
    customerNumber = custNum;
}
public String getCustomerNumber(){
    return customerNumber;
}
public void setCustomerType(String cusType){
    customerType = cusType;
}
public String getCustomerType(){
    return customerType;
}
public void setPurchases(double purch){
    purchases = purch;
}
public double getPurchases(){
    return purchases;
}
public double getTotalOwed(){
    return purchases;
}
public String toString(){ 
      return super.toString() + "\nCustomer Number: " + customerNumber + "\nCustomer Type: " + customerType + 
              "\nTotal Purchases: " + purchases + "\nTotal Owed: " + purchases;
}
}



public class PreferredCustomer extends Customer {
    private double discountPercent=0.0;

    PreferredCustomer(){
        super(DEFAULT_VALUE,DEFAULT_VALUE,DEFAULT_VALUE,DEFAULT_VALUE, DEFAULT_VALUE,0.0);
    }
    PreferredCustomer(String name, String address, String phone, String customerNumber, String customerType, double purchases){
        super (name, address, phone, customerNumber, customerType, purchases);
    }
    public void setDiscountPercent(double dp){
        discountPercent = dp;

    }
    public double getDiscountPercent(){
        if (purchases >= 2000){
            discountPercent = 100 * .10;

        }
        else if (purchases >= 1500 && purchases <2000){
            discountPercent = 100 * .7;
        }
        else if (purchases >= 1000 && purchases <1500){
            discountPercent = 100 * .6;
        }
        else if (purchases >=500 && purchases <1000){
            discountPercent= 100 * .5;
        }
        else if(purchases<500){
            discountPercent = 0;
        }

        return discountPercent ;
    }
    public double getTotalOwed(){
        return purchases - discountPercent;
    }
    public String toString(){ 
      return super.toString() + "\nTotal Discount Percent: " + discountPercent + "\nTotal Owed Minus Discount: " + this.getTotalOwed();
    }
}

Answer 1

从我在您的来源中看到的问题来自getDiscountPercent;你在getter函数中进行计算和修改成员，这是一个坏主意。 getter应该只返回数据而不是修改类的内部状态。

解决方案是创建一个名为calculateDiscountPercent的私有方法，并在修改会影响折扣百分比值的成员时在内部调用它。像这样：

private void calculateDiscountPercent(){
    if (purchases >= 2000){
        discountPercent = 100 * .10;

    }
    else if (purchases >= 1500 && purchases <2000){
        discountPercent = 100 * .7;
    }
    else if (purchases >= 1000 && purchases <1500){
        discountPercent = 100 * .6;
    }
    else if (purchases >=500 && purchases <1000){
        discountPercent= 100 * .5;
    }
    else if(purchases<500){
        discountPercent = 0;
    }
}

从源代码中，我发现discountPercent受其超级类purchases成员的影响。因此，每次购买更改时，覆盖其setter函数以计算折扣。像这样：

@Override
public void setPurchases(double purch){
    super.setPurchases(purch);
    this.calculateDiscountPercent();
}

完整的课程看起来像：

public class PreferredCustomer extends Customer {
    private double discountPercent=0.0;

    PreferredCustomer(){
        super(DEFAULT_VALUE,DEFAULT_VALUE,DEFAULT_VALUE,DEFAULT_VALUE, DEFAULT_VALUE,0.0);
        this.calculateDiscountPercent();
    }
    PreferredCustomer(String name, String address, String phone, String customerNumber, String customerType, double purchases){
        super (name, address, phone, customerNumber, customerType, purchases);
        this.calculateDiscountPercent();
    }
    public void setDiscountPercent(double dp){
        discountPercent = dp;
    }
    public double getDiscountPercent(){
        return discountPercent ;
    }
    @Override
    public void setPurchases(double purch){
        super.setPurchases(purch);
        this.calculateDiscountPercent();
    }
    private void calculateDiscountPercent(){
        if (purchases >= 2000){
            discountPercent = 100 * .10;

        }
        else if (purchases >= 1500 && purchases <2000){
            discountPercent = 100 * .7;
        }
        else if (purchases >= 1000 && purchases <1500){
            discountPercent = 100 * .6;
        }
        else if (purchases >=500 && purchases <1000){
            discountPercent= 100 * .5;
        }
        else if(purchases<500){
            discountPercent = 0;
        }
    }
    public double getTotalOwed(){
        return purchases - discountPercent;
    }
    public String toString(){ 
      return super.toString() + "\nTotal Discount Percent: " + discountPercent + "\nTotal Owed Minus Discount: " + this.getTotalOwed();
    }
}

在继承classe中进行计算

1 个答案: