While循环检查字符输入 [英] While loop to check character input

问题描述

我正在尝试接受来自用户的字符形式的输入.我已经在工作，但是我需要检查并确保它是6个字符(H，h，S，s，L，l)之一.我有一个while循环，但是一旦添加了多个字符语句，循环就会为每个正确的值给出错误.

I am trying to accept input from the user in the form of a character. I have that working but I need to check and make sure it is one of 6 characters (H, h, S, s, L, l). I have a while loop but as soon as add more than one character statement to it, the loop gives the error for every value that should be correct.

这是函数:

    private static char getHighLow(Scanner keyboard) 
{
    System.out.println("High, Low, or Sevens (H/L/S): ");
    String choiceString = keyboard.next();

    char choice = choiceString.charAt(0);

    while (choice != 'H' || choice != 'h' || choice != 'L' || choice != 'l' || choice != 'S' || choice != 's')
    {
        System.out.println("You have entered an invalid entry.");
        System.out.println("High, Low, or Sevens (H/L/S): ");
        choiceString = keyboard.next();
    }

    return choice;

}

继续检查像这样的多个字符的最佳方法是什么?

What is the best way to continue checking for multiple characters like this?

推荐答案

您的逻辑中有一个错误:您应该将这些测试与AND连接:&& :

There is an error in your logic: you should be connecting those tests with AND: &&:

while (choice != 'H' && choice != 'h' && choice != 'L' && ...

此外， choice 永远不会在循环体内进行更新，因此它永远不会改变.在循环中重新读取 choiceString 后，复制 choice = choiceString.charAt(0); .

Furthermore choice is never being updated within the body of the loop, so it will never change. Duplicate the choice = choiceString.charAt(0); after you re-read choiceString within the loop.

从概念上讲，只要字符不是H AND不是L AND不是S ，您就希望继续要求输入.

Conceptually, you want to keep asking for input so long as the character isn't H AND isn't L AND isn't S.

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