How to validate username with regular expression -Regular Expression සමග පරිශීලක නාමය තහවුරු කරන්නේ කෙසේද?

Username Regular Expression Pattern

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

Description

^                    # 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

Whole combination is means, 3 to 15 characters with any lower case character, digit or special symbol “_-” only. This is common username pattern that’s widely use in different websites.

1. Java Regular Expression Example

UsernameValidator.java

package com.javaSchool.regex;
 
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class UsernameValidator{
 
   private Pattern pattern;
   private Matcher matcher;
 
   private static final String USERNAME_PATTERN = "^[a-z0-9_-]{3,15}$";
 
   public UsernameValidator(){
    pattern = Pattern.compile(USERNAME_PATTERN);
   }
 
   /**
    * Validate username with regular expression
    * @param username username for validation
    * @return true valid username, false invalid username
    */
   public boolean validate(final String username){
 
    matcher = pattern.matcher(username);
    return matcher.matches();
 
   }
}

2. Username that match:

1. javaSchool34
2. javaSchool_2002
3. javaSchool-2002
4. js3-4_cool

3. Username that doesn’t match:

1. js (too short, min 3 characters)
2. js@cool (“@” character is not allow)
3. javaSchool123456789_- (too long, max characters of 15)

4. Unit Test – UsernameValidator

Using testNG to perform unit test.

UsernameValidatorTest.java

package com.javaSchool.regex;
 
import org.testng.Assert;
import org.testng.annotations.*;
 
/**
 * Username validator Testing
 * @author javaSchool
 *
 */
public class UsernameValidatorTest {
 
 private UsernameValidator usernameValidator;
 
 @BeforeClass
        public void initData(){
  usernameValidator = new UsernameValidator();
        }
 
 @DataProvider
 public Object[][] ValidUsernameProvider() {
  return new Object[][]{
     {new String[] {
              "javaSchool34", "javaSchool_2002","javaSchool-2002" ,"mk3-4_yong"
     }}
               };
 }
 
 @DataProvider
 public Object[][] InvalidUsernameProvider() {
  return new Object[][]{
     {new String[] {
       "js","js@cool","javaSchool123456789_-"   
     }}
         };
 }
 
 @Test(dataProvider = "ValidUsernameProvider")
 public void ValidUsernameTest(String[] Username) {
 
    for(String temp : Username){
  boolean valid = usernameValidator.validate(temp);
  System.out.println("Username is valid : " + temp + " , " + valid);
  Assert.assertEquals(true, valid);
    }
 
 }
 
 @Test(dataProvider = "InvalidUsernameProvider", 
                 dependsOnMethods="ValidUsernameTest")
 public void InValidUsernameTest(String[] Username) {
 
    for(String temp : Username){
  boolean valid = usernameValidator.validate(temp);
  System.out.println("username is valid : " + temp + " , " + valid);
  Assert.assertEquals(false, valid);
    }
 
 } 
}

5. Unit Test – Result

Username is valid : javaSchool34 , true
Username is valid : javaSchool_2002 , true
Username is valid : javaSchool-2002 , true
Username is valid : mk3-4_yong , true
username is valid : js, false
username is valid : js@cool , false
username is valid : javaSchool123456789_- , false
PASSED: ValidUsernameTest([Ljava.lang.String;@1d4c61c)
PASSED: InValidUsernameTest([Ljava.lang.String;@116471f)
 
===============================================
    com.javaSchool.regex.UsernameValidatorTest
    Tests run: 2, Failures: 0, Skips: 0
===============================================
 
 
===============================================
javaSchool
Total tests run: 2, Failures: 0, Skips: 0
===============================================

JAVA SCHOOL