Question

在while循环中，我使循环在一次无效输入后不会返回有效答案，并重复“错误！客户类型无效。再试一次。”一直到我关闭程序。如果我第一次输入R或C作为输入正常工作。当我输入任何其他内容时，我收到错误消息“错误！客户类型无效。请重试。”就像我应该是故意的。但是在输入r或c之后的错误再次给出了错误，并且我做的任何输入一遍又一遍地返回错误消息，直到我关闭程序。有人可以告诉我，我的代码中有什么错误导致这个吗？

public static String getValidCustomerType(Scanner sc)
{
    String customerType = ("");
      System.out.println("Enter the Customer Type");
      customerType = sc.next() ;
      boolean isValid = false;
      while (isValid == false)
      {
       if (customerType.equalsIgnoreCase("R")|customerType.equalsIgnoreCase("C") ) 
       {
         isValid = true;
       }
       else
       {
          System.out.println("Error! Invalid customer type. Try again ");
       }   
       sc.nextLine() ;
      }
   return customerType ;
}

Answer 1

我认为你必须在while循环中移动输入调用。否则，customerType变量始终相同。

public static String getValidCustomerType(Scanner sc)
{
    String customerType = ("");
      System.out.println("Enter the Customer Type");
      // move this to while loop
      //customerType = sc.next() ;
      boolean isValid = false;
      while (isValid == false)
      {
       // get input here
       customerType = sc.next() ;
       if (customerType.equalsIgnoreCase("R")|customerType.equalsIgnoreCase("C") ) 
       {
         isValid = true;
       }
       else
       {
          System.out.println("Error! Invalid customer type. Try again ");
       }   
       sc.nextLine() ;
      }
   return customerType ;
}

Answer 2

试试这个：|（按位OR）与作为布尔OR运算符的||不同。其次，您没有再次分配customerType - 修复程序如下。

while (isValid == false)
  {
   if (customerType.equalsIgnoreCase("R")||customerType.equalsIgnoreCase("C") ) 
   {
     isValid = true;
   }
   else
   {
      System.out.println("Error! Invalid customer type. Try again ");
   }   
    customerType = sc.nextLine() ;
  }

Answer 3

你没有在while循环中分配给customerType。更好的是把它移到一开始。

public static String getValidCustomerType(Scanner sc)
{
    String customerType = ("");

      boolean isValid = false;
      while (isValid == false)
      {
          System.out.println("Enter the Customer Type");
          customerType = sc.nextLine() ;
       if (customerType.equalsIgnoreCase("R")|customerType.equalsIgnoreCase("C") ) 
       {
         isValid = true;
       }
       else
       {
          System.out.println("Error! Invalid customer type. Try again ");
       }   
      }
   return customerType ;
}

Answer 4

我建议使用带有标记的do while循环。这可以保证代码至少执行once。

    public static String getValidCustomerType(Scanner sc) {
        String customerType;
        boolean isValid = false;

        System.out.println("Enter the Customer Type");

        do {
            customerType = sc.next();

            if (customerType.equalsIgnoreCase("R")|customerType.equalsIgnoreCase("C") )  {
                isValid = true;
            } else {
                System.out.println("Error! Invalid customer type. Try again ");
            }   
        } while(!isValid);

        return customerType ;
    }

while循环在第一个错误之后反复返回错误

4 个答案: