Java While循环在第一个错误之后反复返回错误

在一个while循环中，我使循环在一个无效输入后不会返回有效答案，并重复错误！无效的客户类型。再试一次。一遍又一遍直到我关闭程序。如果我第一次输入R或C，它工作正常。当我输入任何其他内容并收到错误消息error！无效的客户类型。再试一次。我应该是故意的。然而，在那个错误之后，输入r或c会再次给我错误，我所做的任何输入都会反复返回错误消息，直到我关闭程序为止。有人能告诉我我的代码中有什么错误导致了这个吗

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 ;
} 

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我认为您必须将输入调用移动到while循环中。否则customerType变量总是相同的

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 ;
} 

尝试以下操作：|按位OR与| |不同，后者是布尔OR运算符。其次，您没有再次分配customerType-修复方法如下

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() ;
  }

您不会在while循环中指定给customerType。最好还是从头开始

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 ;
} 

---

我建议对sentinel使用do while循环。这保证了代码至少被执行

---

每次在循环中都需要分配customerType

    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 ;
    }