Регулярное выражение Java проверяет примеры паролей

  ^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[!@#&()â€"[{}]:;',?/*~$^+=<>]).{8,20}$

^                                   # start of line
  (?=.*[0-9])                       # positive lookahead, digit [0-9]
  (?=.*[a-z])                       # positive lookahead, one lowercase character [a-z]
  (?=.*[A-Z])                       # positive lookahead, one uppercase character [A-Z]
  (?=.*[!@#&()â€"[{}]:;',?/*~$^+=<>]) # positive lookahead, one of the special character in this [..]
  .                                 # matches anything
  {8,20}                            # length at least 8 characters and maximum of 20 characters
$                                   # end of line

package com.mkyong.regex.password;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class PasswordValidator {

    // digit + lowercase char + uppercase char + punctuation + symbol
    private static final String PASSWORD_PATTERN =
            "^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[!@#&()â€"[{}]:;',?/*~$^+=<>]).{8,20}$";

    private static final Pattern pattern = Pattern.compile(PASSWORD_PATTERN);

    public static boolean isValid(final String password) {
        Matcher matcher = pattern.matcher(password);
        return matcher.matches();
    }

}

package com.mkyong.regex.password;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;

import java.util.stream.Stream;

import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;

public class PasswordValidatorTest {

    @ParameterizedTest(name = "#{index} - Run test with password = {0}")
    @MethodSource("validPasswordProvider")
    void test_password_regex_valid(String password) {
        assertTrue(PasswordValidator.isValid(password));
    }

    @ParameterizedTest(name = "#{index} - Run test with password = {0}")
    @MethodSource("invalidPasswordProvider")
    void test_password_regex_invalid(String password) {
        assertFalse(PasswordValidator.isValid(password));
    }

    static Stream validPasswordProvider() {
        return Stream.of(
                "AAAbbbccc@123",
                "Hello world$123",
                "A!@#&()â€"a1",               // test punctuation part 1
                "A[{}]:;',?/*a1",           // test punctuation part 2
                "A~$^+=<>a1",               // test symbols
                "0123456789$abcdefgAB",     // test 20 chars
                "123Aa$Aa"                  // test 8 chars
        );
    }

    // At least
    // one lowercase character,
    // one uppercase character,
    // one digit,
    // one special character
    // and length between 8 to 20.
    static Stream invalidPasswordProvider() {
        return Stream.of(
                "12345678",                 // invalid, only digit
                "abcdefgh",                 // invalid, only lowercase
                "ABCDEFGH",                 // invalid, only uppercase
                "abc123$$$",                // invalid, at least one uppercase
                "ABC123$$$",                // invalid, at least one lowercase
                "ABC$$$$$$",                // invalid, at least one digit
                "java REGEX 123",           // invalid, at least one special character
                "java REGEX 123 %",         // invalid, % is not in the special character group []
                "________",                 // invalid
                "--------",                 // invalid
                " ",                        // empty
                "");                        // empty
    }
}