JAVA EE: How to write a regex to validate the password

Thursday 21 December 2017

How to write a regex to validate the password | Regex in java

Click here to watch on Youtube :
https://www.youtube.com/watch?v=Bwc6apOcMlA&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

How to write a regex to validate the password | Regex in java

PasswordValidator.java

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/**

 * 

 * How to validate password with regular expression

 *

 */

public class PasswordValidator

{

    private Pattern pattern;

    private Matcher matcher;

    private static final String PASSWORD_REGEX = 

                      "((?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{6,20})";

    public PasswordValidator()

    {

        pattern = Pattern.compile(PASSWORD_REGEX);

    }

    /**

     * Validate password with regular expression

     * 

     * @param password  password for validation

     * @return true valid password, false invalid password

     */

    public boolean validate(final String password)

    {

        matcher = pattern.matcher(password);

        return matcher.matches();

    }

}

RegexDemo.java

/**

 * 

 * How to validate password with regular expression

 *

 */

public class RegexDemo

{

    public static void main(String[] args)

    {

        PasswordValidator passwordValidator = new PasswordValidator();

        System.out.println("'peter1AB@' is valid? = "+passwordValidator.validate("peter1AB@"));

        System.out.println("'peter4COW$' is valid?  = "+passwordValidator.validate("peter4COW$"));

        System.out.println("'peter78Dog%#' is valid?  = "+passwordValidator.validate("peter78Dog%#"));

        System.out.println("--------------------------------------------------");

        /*

         *  too short, minimum 6 characters

         */

        System.out.println("'p1AB@' is valid? = "+passwordValidator.validate("p1AB@"));

        /*

         *  uppercase characters is required

         */

        System.out.println("'peter1@' is valid? = "+passwordValidator.validate("peter1@"));

        /*

         *  special symbol “*" is not allow here

         */

        System.out.println("'peterAB2*' is valid? = "+passwordValidator.validate("peterAB2*"));

        /*

         *  digit is required

         */

        System.out.println("'peterAB$' is valid? = "+passwordValidator.validate("peterAB$"));

        /*

         *  lower case character is required

         */

        System.out.println("'PETER2$' is valid? = "+passwordValidator.validate("PETER2$"));

    }

}

Output

'peter1AB@' is valid? = true

'peter4COW$' is valid?  = true

'peter78Dog%#' is valid?  = true

--------------------------------------------------

'p1AB@' is valid? = false

'peter1@' is valid? = false

'peterAB2*' is valid? = false

'peterAB$' is valid? = false

'PETER2$' is valid? = false