Java Regex expressions for Passwords

Question

I've just created this class for a password validation

 /* 
 *  ^                         Start anchor
 *  (?=.*[A-Z].*[A-Z])        Ensure string has two uppercase letters.
 *  (?=.*[!@#$&*])            Ensure string has one special case letter.
 *  (?=.*[0-9].*[0-9])        Ensure string has two digits.
 *  (?=.*[a-z].*[a-z].*[a-z]) Ensure string has three lowercase letters.
 *  .{8}                      Ensure string is of length 8.
 *  $                         End anchor.
 */
public class PasswordUtils {

    private static final String PWD_REGEX = "^(?=.*[A-Z].*[A-Z])(?=.*[!@#$&*])(?=.*[0-9].*[0-9])(?=.*[a-z].*[a-z].*[a-z])";

    /**
     * Non instantiable.
     */
    private PasswordUtils() {
        throw new AssertionError("Non instantiable");
    }

    public static boolean match (String pwd1, String pwd2) {
        return StringUtils.equals(pwd1, pwd2);
    }

    public static boolean isStrong(String password){
        return password.matches(PWD_REGEX);
     }
}

Then this Junit, but it seems that the pwd does not match the requirements of the regular expression

private final String PWD6 = "Pi89pR&s";

@Test
public void testStrong () {
    assertTrue(PasswordUtils.isStrong(PWD6));
}

It's easier not to use regex. Just iterate the string one char at a time, counting the number of upper case, lower case etc. Then ensure the counts meet your criteria. — Andy Turner
– Andy Turner, Commented May 7, 2017 at 16:19

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Try this hope this will help you out..

Regex: ^(?=.*?[A-Z].*?[A-Z])(?=.*?[a-z].*?[a-z].*?[a-z])(?=.*?[\d].*?[\d])(?=.*?[^\w]).{8}$

1. ^ start of string.

2. (?=.*?[A-Z].*?[A-Z]) positive look ahead for two uppercase characters.

3. (?=.*?[a-z].*?[a-z].*?[a-z]) positive look ahead for three lowercase characters.

4. (?=.*?[\d].*?[\d]) positive look ahead for two digits.

5. (?=.*?[^\w]) positive look ahead for non-word character

6. .{8} will match exactly 8 characters.

7. $ end of string.

Regex code demo

edited Jun 20, 2020 at 9:12

CommunityBot

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answered May 7, 2017 at 16:26

Sahil Gulati

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Comments

Chris · Accepted Answer · 2017-05-07 16:22:32Z

1

Try this:

(?=(?:.*[A-Z]){2})(?=(?:.*[a-z]){2})(?=(?:.*[0-9]){2})(?=(?:.*[!@#$&*]){1}).{8}

The basic idea is:

(?=(?:.*[GROUP]){NUMBER})

Where GROUP is the grouping you want to match (i.e A-Z) and NUMBER is how many.

Also note, you can use {NUMBER,} if you want to match NUMBER or more occurrences of each group.

https://regex101.com/r/JGtIkF/1

answered May 7, 2017 at 16:22

Chris

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