Java if语句及其应写的顺序

我需要开发一个算法来计算票价。首先，用户必须输入价格，座位位置上限=30%折扣，中间=普通，下限=25%溢价，客户类型高级=10%折扣，成人=普通

因此，一个示例测试：用户输入50表示价格，输入上限表示位置，输入高级表示客户类型，最终票价应为31.50

到目前为止，我的算法得到了35。有人能找出我的错误吗

    if (cusType.charAt(0) == 'A'){
        ticPrice = regTicPrice;

        if (location.charAt(0) == 'U'){
            ticPrice = regTicPrice * 0.7;
        }
        else if (location.charAt(0) == 'L'){
            ticPrice = regTicPrice * 1.25;
        }
        else if (location.charAt(0) == 'M'){
            ticPrice = regTicPrice;
        }
    }

    else if (cusType.charAt(0) == 'S'){
        ticPrice = regTicPrice * 0.9;

        if (location.charAt(0) == 'U'){
            ticPrice = regTicPrice * 0.7;
        }
        else if (location.charAt(0) == 'L'){
            ticPrice = regTicPrice * 1.25;
        }
        else if (location.charAt(0) == 'M'){
            ticPrice = regTicPrice;
        }
    }
    else{
     ticPrice = 0;   
    }

---

您的问题与您更新ticPrice有关，但在成为高级会员后，您永远不会重复使用更新后的ticPrice

你最终为你做了50*.7而不是50*.9*.7

if (cusType.charAt(0) == 'A'){
    ticPrice = regTicPrice;

    if (location.charAt(0) == 'U'){
        ticPrice = ticPrice * 0.7;
    }
    else if (location.charAt(0) == 'L'){
        ticPrice = ticPrice * 1.25;
    }
    else if (location.charAt(0) == 'M'){
        // you don't technically need this if statement at the end since it doesnt change
        ticPrice = ticPrice;
    }
}

else if (cusType.charAt(0) == 'S'){
    ticPrice = ticPrice * 0.9;

    if (location.charAt(0) == 'U'){
        ticPrice = ticPrice * 0.7;
    }
    else if (location.charAt(0) == 'L'){
        ticPrice = ticPrice * 1.25;
    }
    else if (location.charAt(0) == 'M'){
        // you dont technically need this if statement at the end since it doesnt change
        ticPrice = ticPrice;
    }
}
else{
 ticPrice = 0;   
}

使用HashMap使您的生活更简单，如下所示：

HashMap customerTypeDiscount = new HashMap<String, Double>();
customerTypeDiscount.put("Adult", 1);
customerTypeDiscount.put("Senior", 0.9);

HashMap locationDiscount = new HashMap<String, Double>();
locationDiscount.put("Upper", 0.7);
locationDiscount.put("Middle", 1);
locationDiscount.put("Lower", 1.25);

ticPrice = regTicPrice * ((Double) customerTypeDiscount.get(cusType)) * (((Double) locationDiscount.get(location));

---

在计算机票折扣价格时，您使用的是机票的实际价格，请在内部If中使用ticPrice，而不是下面的REGICPRICE sa：

   if (cusType.charAt(0) == 'A'){
    ticPrice = regTicPrice;
    if (location.charAt(0) == 'U'){
        ticPrice = ticPrice * 0.7;
    }
    else if (location.charAt(0) == 'L'){
        ticPrice = ticPrice * 1.25;
    }
    else if (location.charAt(0) == 'M'){
        ticPrice = ticPrice;
    }
}

else if (cusType.charAt(0) == 'S'){
    ticPrice = regTicPrice * 0.9;

    if (location.charAt(0) == 'U'){
        ticPrice = ticPrice * 0.7;
    }
    else if (location.charAt(0) == 'L'){
        ticPrice = ticPrice * 1.25;
    }
    else if (location.charAt(0) == 'M'){
        ticPrice = ticPrice;
    }
}
else{
 ticPrice = 0;   
}

---

检查您编写的这行代码：

ticPrice = regTicPrice * 0.9;

    if (location.charAt(0) == 'U'){
        ticPrice = regTicPrice * 0.7;
    }

价格是50英镑

ticPrice =  regTicPrice * 0.9

现在ticPrice的值为50*0.9=45

下一行是

ticPrice = regTicPrice * 0.7
Wrong ==== ticPrice = 50 * 0.7 = 35
Right ==== ticPrice = 45 * 0.7 = 31.50

您正在使用regTicPrice*0.7覆盖ticPrice:

代码应该如下所示

ticPrice = regTicPrice * 0.9;

    if (location.charAt(0) == 'U'){
        ticPrice = ticPrice * 0.7;
    }

您必须为ticPrice使用float数据类型，如果您已经在使用它，那么请尝试ticPrice=floatticPrice*0.9

重构和修复

ticPrice = 0; 

if (cusType.charAt(0) == 'A')
    ticPrice = regTicPrice;
else if (cusType.charAt(0) == 'S')
    ticPrice = regTicPrice * 0.9;

if (ticPrice > 0) {
    if (location.charAt(0) == 'U')
        ticPrice = ticPrice * 0.7;
    else if (location.charAt(0) == 'L')
        ticPrice = ticPrice * 1.25;
}

---

使用hashmap存储您的信息，如果cusType.charAt0=='A'，则从这里选择{ ticPrice=regTicPrice

    if (location.charAt(0) == 'U'){
        ticPrice = ticPrice * 0.7;      //you made mistake here..
    }
    else if (location.charAt(0) == 'L'){
        ticPrice = ticPrice * 1.25;
    }
    else if (location.charAt(0) == 'M'){
        ticPrice = regTicPrice;
    }
}

else if (cusType.charAt(0) == 'S'){
    ticPrice = regTicPrice * 0.9;

    if (location.charAt(0) == 'U'){
        ticPrice = ticPrice * 0.7;
    }
    else if (location.charAt(0) == 'L'){
        ticPrice = ticPrice * 1.25;
    }
    else if (location.charAt(0) == 'M'){
        ticPrice = regTicPrice;
    }
}
else{
 ticPrice = 0;   
}

一旦你得到了可爱的类型Senior:50*0.9=45=ticPrice。

---

现在再次需要对loactionUpper应用折扣：45*0.7=31.5.=>ticPrice*0.7.而不是regTicPrice*0.7

ticPrice=regTicPrice*0.7应该是ticPrice=ticPrice*0.7；请以后使用调试器处理此类问题。好的，现在我只得到if语句后半部分的输出，如果charAt0==“S”，而不是“A”处的字符