Validate password in java

In this post, we will see how to validate a password in java.
Here are rules for password:

Must have at least one numeric character
Must have at least one lowercase character
Must have at least one uppercase character
Must have at least one special symbol among @#$%
Password length should be between 8 and 20

Table of Contents [hide]

Using regex
Using String’s matches method

Using regex

Here is standard regex for validating password.

^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{8,20}$

^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{8,20}$

Here is explanation for above regex

^ asserts position at start of a line
Group (?=.*\\d)
Assert that the Regex below matches
.* matches any character (except for line terminators)
\\ matches the character \ literally (case sensitive)
d matches the character d literally (case sensitive)
Group (?=.*[a-z])
Assert that the Regex below matches
.* matches any character (except for line terminators)
Match a single character present in the list below [a-z]
a-z a single character in the range between a (index 97) and z (index 122) (case sensitive)
Group (?=.*[A-Z])
Assert that the Regex below matches
.* matches any character (except for line terminators)
Match a single character present in the list below [A-Z]
A-Z a single character in the range between A (index 65) and Z (index 90) (case sensitive)
Group (?=.*[@#$%])
Assert that the Regex below matches
.* matches any character (except for line terminators)
Match a single character present in the list below [@#$%]
@#$% matches a single character in the list @#$% (case sensitive)
.{8,20} matches any character (except for line terminators)
{8,20} Quantifier — Matches between 8 and 20 times, as many times as possible, giving back as needed (greedy)
$ asserts position at the end of a line

Here is java program to implement it.

package org.arpit.java2blog;

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

public class RegexCurrencySymbol {

    public static void main(String args[]) {
        String password1 = "Java2blog@";

        String regex = "^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{8,20}$";
        boolean validPassword = isValidPassword(password1,regex);
        System.out.println("Java2blog@ is valid password:" +validPassword);

        String password2 = "helloword#123";

        String regex1 = "^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{8,20}$";
        boolean validPassword1 = isValidPassword(password2,regex1);
        // No upper case
        System.out.println("helloword#123 is valid password:" +validPassword1);
    }

    public static boolean isValidPassword(String password,String regex)
    {
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(password);
        return matcher.matches();
    }
}

package org.arpit.java2blog;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

public class RegexCurrencySymbol {

public static void main(String args[]) {

String password1 = "Java2blog@";

String regex = "^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{8,20}$";

boolean validPassword = isValidPassword(password1,regex);

System.out.println("Java2blog@ is valid password:" +validPassword);

String password2 = "helloword#123";

String regex1 = "^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{8,20}$";

boolean validPassword1 = isValidPassword(password2,regex1);

// No upper case

System.out.println("helloword#123 is valid password:" +validPassword1);

}

public static boolean isValidPassword(String password,String regex)

{

Pattern pattern = Pattern.compile(regex);

Matcher matcher = pattern.matcher(password);

return matcher.matches();

}

Output:

Java2blog@ is valid password:true
helloword#123 is valid password:false

Using String’s matches method

We can also use string’s matches() method to validate password in java.
Let’s see with the help of an example.

package org.arpit.java2blog;

public class PasswordValidatorMain {

    public static void main(String args[]) {
        String password1 = "Java2blog@";

        boolean validPassword = isValidPassword(password1);
        System.out.println("Java2blog@ is valid password:" +validPassword);

        String password2 = "helloword#123";

        boolean validPassword1 = isValidPassword(password2);
        // No upper case
        System.out.println("helloword#123 is valid password:" +validPassword1);
    }

    /**
     * Method to check if password is valid or not.
     * @param password
     * @return boolean
     */
    public static boolean isValidPassword(String password)
    {
            boolean isValid = true;
            if (password.length() > 15 || password.length() < 8)
            {
                    System.out.println("Password must be less than 20 and more than 8 characters in length.");
                    isValid = false;
            }
            String upperCaseChars = "(.*[A-Z].*)";
            if (!password.matches(upperCaseChars ))
            {
                    System.out.println("Password must have atleast one uppercase character");
                    isValid = false;
            }
            String lowerCaseChars = "(.*[a-z].*)";
            if (!password.matches(lowerCaseChars ))
            {
                    System.out.println("Password must have atleast one lowercase character");
                    isValid = false;
            }
            String numbers = "(.*[0-9].*)";
            if (!password.matches(numbers ))
            {
                    System.out.println("Password must have atleast one number");
                    isValid = false;
            }
            String specialChars = "(.*[@,#,$,%].*$)";
            if (!password.matches(specialChars ))
            {
                    System.out.println("Password must have atleast one special character among @#$%");
                    isValid = false;
            }
            return isValid; 
    }
}

package org.arpit.java2blog;

public class PasswordValidatorMain {

public static void main(String args[]) {

String password1 = "Java2blog@";

boolean validPassword = isValidPassword(password1);

System.out.println("Java2blog@ is valid password:" +validPassword);

String password2 = "helloword#123";

boolean validPassword1 = isValidPassword(password2);

// No upper case

System.out.println("helloword#123 is valid password:" +validPassword1);

}

/**

* Method to check if password is valid or not.

* @param password

* @return boolean

public static boolean isValidPassword(String password)

{

boolean isValid = true;

if (password.length() > 15 || password.length() < 8)

{

System.out.println("Password must be less than 20 and more than 8 characters in length.");

isValid = false;

}

String upperCaseChars = "(.*[A-Z].*)";

if (!password.matches(upperCaseChars ))

{

System.out.println("Password must have atleast one uppercase character");

isValid = false;

}

String lowerCaseChars = "(.*[a-z].*)";

if (!password.matches(lowerCaseChars ))

{

System.out.println("Password must have atleast one lowercase character");

isValid = false;

}

String numbers = "(.*[0-9].*)";

if (!password.matches(numbers ))

{

System.out.println("Password must have atleast one number");

isValid = false;

}

String specialChars = "(.*[@,#,$,%].*$)";

if (!password.matches(specialChars ))

{

System.out.println("Password must have atleast one special character among @#$%");

isValid = false;

}

return isValid;

}

Output:

Java2blog@ is valid password:true
Password must have atleast one uppercase character
helloword#123 is valid password:false

That’s all about how to validate password in java.

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Validate password in java

Using regex

Using String’s matches method

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