java - 无效的正则表达式 java : unclosed character class

Question

我正在尝试用 java 编写 emailValidator 函数，但遇到问题:

public static boolean EmailValidator(String mail) {
    Pattern pattern;
    Matcher matcher;

    pattern = Pattern.compile("^[A-Za-z0-9\\]{2,2}(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]{2,2}(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,4})$");
    matcher = pattern.matcher(mail);

    return matcher.matches();
}

错误

Exception in thread "main" java.util.regex.PatternSyntaxException: Unclosed character class near index 89
^[A-Za-z0-9\]{2,2}(\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]{2,2}(\.[A-Za-z0-9]+)*(\.[A-Za-z]{2,4})$

请问有人可以告诉我我必须做什么来解决这个问题，非常感谢

Answer 1

您已经转义了开头的结束字符类字符:

^[A-Za-z0-9\\]

记住，在字符串解释之后，它变成:

^[A-Za-z0-9\]

由于您可能想包含反斜杠，请尝试对其进行双重编码:

^[A-Za-z0-9\\\\]

这成为转义的反斜杠:

^[A-Za-z0-9\\]