根据id计算年龄答案

【问题标题】：calculate age based on id根据id计算年龄
【发布时间】：2021-05-27 12:59:26
【问题描述】：

public int payment(){

        int Carpayment;
        int hour;
        String type;
        
        if (type == "MyVi")
            Carpayment = 10 * hour;
        else 
            if (type == "Iswara")
                Carpayment = 15 * hour;
        else 
            if (type == "Waja")
                Carpayment = 20 * hour;
        else 
            if (type == "Vios")
                Carpayment = 25 * hour;
        else 
            if (type == "Civic")
                Carpayment = 30 * hour; 
        
        return Carpayment;
     }

当我运行此代码时.. 错误 Carpayment 可能尚未初始化

【问题讨论】：

您应该不将Strings 与== 进行比较，为此使用equals。 See here.

标签： java if-statement

【解决方案1】：

你可以做的一些整改

比较 type == "MyVi" ，您不应该将 String 与 == 运算符进行比较，因为它将比较对象，即哈希码比较。你应该使用 type.equals("MyVi");

您不应使用局部变量来计算汽车付款，因为它们需要初始化，因此您应该将它们传递给付款方式或将它们用作实例变量。

public int payment(int Carpayment,int hour,String type){

    //int Carpayment;
    //int hour;
    //String type;

    if (type == "MyVi")
        Carpayment = 10 * hour;
    else 
        if (type == "Iswara")
            Carpayment = 15 * hour;
    else 
        if (type == "Waja")
            Carpayment = 20 * hour;
    else 
        if (type == "Vios")
            Carpayment = 25 * hour;
    else 
        if (type == "Civic")
            Carpayment = 30 * hour; 

    return Carpayment;
 }

3.你可以这样做

    Class Car {
       int Carpayment;
       int hour;
       String type;
       Car(int hour,String type) {
       this.hour = hour;
       this.type = type;
       }
       public int payment(){

            if (type == "MyVi")
                Carpayment = 10 * hour;
            else 
                if (type == "Iswara")
                    Carpayment = 15 * hour;
            else 
                if (type == "Waja")
                    Carpayment = 20 * hour;
            else 
                if (type == "Vios")
                    Carpayment = 25 * hour;
            else 
                if (type == "Civic")
                    Carpayment = 30 * hour; 

            return Carpayment;
         }
       }
       Car civic_1 = new Car(4,"Civic");
       System.out.println(civic_1.payment());//Prints the Car payment to be done

【讨论】：

【解决方案2】：

这是因为您没有最后一个 else 子句。因此，您可以通过所有 if 并且不要进入任何人。要解决此问题，您可以：

使用默认值初始化 Carpayment 变量（我认为更好的选择）；

public int  payment(){
 int Carpayment;
         int hour;
         String type;

 if (type == "MyVi")
     Carpayment = 10 * hour;
 else 
     if (type == "Iswara")
         Carpayment = 15 * hour;
 else 
     if (type == "Waja")
         Carpayment = 20 * hour;
 else 
     if (type == "Vios")
         Carpayment = 25 * hour;
 else 
     if (type == "Civic")
         Carpayment = 30 * hour; 

 return Carpayment;
}

或

在最后一个 else if 中加入最后一个 else 子句。

public int  payment(){
 int Carpayment;
         int hour;
         String type;

 if (type == "MyVi")
     Carpayment = 10 * hour;
 else 
     if (type == "Iswara")
         Carpayment = 15 * hour;
 else 
     if (type == "Waja")
         Carpayment = 20 * hour;
 else 
     if (type == "Vios")
         Carpayment = 25 * hour;
 else 
     if (type == "Civic")
         Carpayment = 30 * hour;
 else 
   Carpayment = 0;

 return Carpayment;
}

【讨论】：