How can I use Pattern and Matcher with StringBuffer or char[] types instead of String?

Question

How can I use a method like this

private boolean respectPattern(String password) {
  Pattern passwordPattern = Pattern.compile(
    "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[.@$!%*?&])[A-Za-z\\d@$!%*?&.]{8,}$",
    Pattern.CASE_INSENSITIVE);
  Matcher matcher = passwordPattern.matcher(password);
  return matcher.find();
}

If I replace password type with StringBuffer or char[]?

Answer 1

Method matcher() in class java util.regex.Pattern takes a single parameter whose type is CharSequence which is an interface. According to the javadoc, there are several implementing classes, including StringBuffer. If none of the existing implementations are suitable for your needs, you can always write your own implementation.

For example, using a CharBuffer

CharBuffer cb = CharBuffer.allocate(11);
cb.put(new char[]{'S','e','c', 'r', 'e', 't', ' ', 'P', 'a', 's', 's'});
Pattern passwordPattern = Pattern.compile(
                "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[.@$!%*?&])[A-Za-z\\d@$!%*?&.]{8,}$",
                Pattern.CASE_INSENSITIVE);
Matcher matcher = passwordPattern.matcher(cb);

Answer 2

if I replace password type with StringBuffer or char[]?

If you replace password type with StringBuffer:

Use as it is i.e. the following will compile successfully and work as intended:

private boolean respectPattern(StringBuffer password) {
    Pattern passwordPattern = Pattern.compile(
            "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[.@$!%*?&])[A-Za-z\\d@$!%*?&.]{8,}$",
            Pattern.CASE_INSENSITIVE);
    Matcher matcher = passwordPattern.matcher(password);
    return matcher.find();
}

If you replace password type with char[]:

Use passwordPattern.matcher(String.valueOf(password));