Java Regex Username Password example

Java Regex Username Password examples

User name Regex Pattern

^[a-z0-9_-]{3,15}$
Split this pattern

^	Start of the line
[a-z0-9_-]	Match characters and symbols in the list, a-z, 0-9 , underscore , hyphen
{3,15}	Length at least 3 characters and maximum length of 15
$	End of the line

Password Regular Expression Pattern

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

(	Start of group
(?=.*\d)	must contains one digit from 0-9
(?=.*[a-z])	must contains one lowercase characters
(?=.*[A-Z])	must contains one uppercase characters
(?=.*[@#$%])	must contains one special symbols in the list "@#$%"
.	match anything with previous condition checking
{6,20}	length at least 6 characters and maximum of 20
)	End of group

Example

package mycollectiontest;

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

public class RegexExample {
   private Pattern pattern;
   private Matcher matcher;
   private static final String USERNAME_PATTERN = "^[a-z0-9_-]{3,15}$";
   private static final String PASSWORD_PATTERN = "((?=.*\\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{6,20})";

   public RegexExample() {
      pattern = Pattern.compile(USERNAME_PATTERN);
      System.out.println("input : pretech user name " + validate("pretech"));
      pattern = Pattern.compile(PASSWORD_PATTERN);
      System.out.println("input : password " + validate("pretech@gmail.com"));
   }

   public boolean validate(final String username) {

      matcher = pattern.matcher(username);
      return matcher.matches();
   }

   public static void main(String[] args) {
      new RegexExample();
   }
}

Output

 

input : pretech user name true

input : password    false