Archives: Validations

Java – Date Validation with Regular Expression

Date Format (dd/mm/yyyy) Regular Expression Pattern

(0?[1-9]|[12][0-9]|3[01])/(0?[1-9]|1[012])/((19|20)\\d\\d)

The above regular expression is used to validate the date format in “dd/mm/yyyy”, you can easy customize to suit your need. However, it’s a bit hard to validate the leap year, 30 or 31 days of a month, we may need basic logic as below.


Java – Password Validation with Regular Expression

Password Regular Expression Pattern:

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

Description:

( # 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

?= – means apply the assertion condition, meaningless by itself, always work with other combination

Whole combination is means, 6 to 20 characters string with at least one digit, one upper case letter, one lower case letter and one special symbol (“@#$%”). This regular expression pattern is very useful to implement a strong and complex password.

[code lang=”java”]import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class PasswordValidator {

private Pattern pattern;
private Matcher matcher;

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

public PasswordValidator() {
pattern = Pattern.compile(PASSWORD_PATTERN);
}

/**
* 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();

}

}[/code]


Java – URL Validation using Commons UrlValidator

[code lang=”java”]import org.apache.commons.validator.UrlValidator;

public class ValidateUrlExample {

public static void main(String[] args) {

UrlValidator urlValidator = new UrlValidator();

//valid URL
if (urlValidator.isValid("http://www.javac.in")) {
System.out.println("url is valid");
} else {
System.out.println("url is invalid");
}

//invalid URL
if (urlValidator.isValid("http://invalidURL^$&%$&^")) {
System.out.println("url is valid");
} else {
System.out.println("url is invalid");
}

}
}[/code]