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 @#$%
- Password length should be between 8 and 20
Table of Contents
Using regex
Here is standard regex for validating password.
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^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{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
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.
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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
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.
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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
Password must have atleast one uppercase character
helloword#123 is valid password:false
That’s all about how to validate password in java.
