java - Java char 比较似乎不起作用

Question

我知道您可以将 Java 中的字符与普通运算符进行比较，例如anysinglechar == y. 但是，我对此特定代码有疑问：

do{ 
    System.out.print("Would you like to do this again? Y/N\n");
    looper = inputter.getChar();
    System.out.print(looper);
    if(looper != 'Y' || looper != 'y' || looper != 'N' || looper != 'n')
        System.out.print("No valid input. Please try again.\n");
}while(looper != 'Y' || looper != 'y' || looper != 'N' || looper != 'n');

问题不应该是其他方法，inputter.getChar()，但无论如何我都会转储它：

private static BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
public static char getChar() throws IOException{
    int buf= read.read();
    char chr = (char) buf;
    while(!Character.isLetter(chr)){
        buf= read.read();
        chr = (char) buf;
    }
    return chr;
}

我得到的输出如下：

Would you like to do this again? Y/N
N
NNo valid input. Please try again.
Would you like to do this again? Y/N
n
nNo valid input. Please try again.
Would you like to do this again? Y/N

如您所见，我输入的字符是n. 然后它被正确打印出来（因此它会被看到两次）。然而，这种比较似乎并不成立。

我确定我忽略了一些明显的东西。

Answer 1

你的逻辑不正确。总是true那looper不是'Y' 或不是'y' 或不是...

您需要“and”的逻辑运算符：&&

if(looper != 'Y' && looper != 'y' && looper != 'N' && looper != 'n')

和你的情况类似的变化while。

Answer 2

||与其将逻辑运算符从to修复，不如&&让代码更清晰：

private static final Set<Character> YES_OR_NO = Set.of('Y', 'y', 'N', 'n');

do { 
    System.out.print("Would you like to do this again? Y/N\n");
    looper = inputter.getChar();
    System.out.print(looper);
    if (!YES_OR_NO.contains(looper))
        System.out.print("No valid input. Please try again.\n");
} while(!YES_OR_NO.contains(looper));