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Wednesday, 19 September 2012

Java Regex Username Password example

01:58

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

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