How to validate the password by using regular expression in java

It is good to use regular expression to validate the password , rather than using validation functions . Regular expression is very easy and simple to modify .

Conditions to validate the password

(?=.*[A-Z])………: At least one capital alphabet .

(?=.*[a-z])………: At least one small alphabet .

(?=.*[\\d])……….: At least one number.

(?=.*[@$#%])..: At least one special character in @$#%.

(?!.*\\s)………. …: Not contain blank space .

.{6,17}……………: Length between 6 to 17 characters.

(?=.*[A-Z])(?=.*[a-z])(?=.*[\\d])(?=.*[@$#%])(?!.*\\s).{6,17}

Example to validate the password :

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class passwordValidation {
   public static void main(String[] args)
    {
    String password[] = new String[5];
           password[0] = "P@ssw0rd";//valid password
           password[1] = "P@ssword";//no number
           password[2] = "Passw0rd";//no special character
           password[3] = "p@ssw0rd";//no capital alphabet
           password[4] = "password";//all small alphabets
    String regex = "(?=.*[A-Z])(?=.*[a-z])(?=.*[\\d])(?=.*[@$#%])(?!.*\\s).{6,17}";
    Pattern pattern = Pattern.compile(regex);
    for(String passwordcheck : password)
    {
    Matcher match = pattern.matcher(passwordcheck);
    boolean status = match.matches();
    System.out.println(passwordcheck+" validation is "+status);
    }
    }
}

import java.util.regex.Pattern;

import java.util.regex.Matcher;

public class passwordValidation {

public static void main(String[] args)

{

String password[] = new String[5];

password[0] = "P@ssw0rd";//valid password

password[1] = "P@ssword";//no number

password[2] = "Passw0rd";//no special character

password[3] = "p@ssw0rd";//no capital alphabet

password[4] = "password";//all small alphabets

String regex = "(?=.*[A-Z])(?=.*[a-z])(?=.*[\\d])(?=.*[@$#%])(?!.*\\s).{6,17}";

Pattern pattern = Pattern.compile(regex);

for(String passwordcheck : password)

{

Matcher match = pattern.matcher(passwordcheck);

boolean status = match.matches();

System.out.println(passwordcheck+" validation is "+status);

}

Execution Result:

P@ssw0rd validation is true
P@ssword validation is false
Passw0rd validation is false
p@ssw0rd validation is false
password validation is false

P@ssw0rd validation is true

P@ssword validation is false

Passw0rd validation is false

p@ssw0rd validation is false

password validation is false

validate the password Returns true if the password satisfied all validations , false otherwise.

validate the password change {6,17} values to set password maximum and minimum length .

So these are the basic and common conditions to validate the password .

How to validate email address by using regular expression in java

Current Tutorials	Books & Pdf's to Download	API Documentations
Java Basics	Beginning java	Java SE 7 API
Java SE	Head First Java	Sun Certified Programmer for Java(SCJP)
LDAP	Java Programming in 24 hours	Sun Certified Web Component Developer
SQL/PLSQL	Servlets Study guide	SQL & PL/SQL Documentation
Servlets	Web Services (Java)	hibernate Api (4.3)
Integrations	Oracle SQL Study guide	Spring Api (4.2)
Web Services	IBM LDAP Book Study guide	Struts Api (1.3)