How to validate email address with regular expression -Regular Expression සමග ඊ-තැපැල් ලිපිනයක් තහවුරු කරන්නේ කෙසේද?

Email Regular Expression Pattern

^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*
      @[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$;

Description

^   #start of the line
  [_A-Za-z0-9-\\+]+ #  must start with string in the bracket [ ], must contains one or more (+)
  (   #   start of group #1
    \\.[_A-Za-z0-9-]+ #     follow by a dot "." and string in the bracket [ ], must contains one or more (+)
  )*   #   end of group #1, this group is optional (*)
    @   #     must contains a "@" symbol
     [A-Za-z0-9-]+      #       follow by string in the bracket [ ], must contains one or more (+)
      (   #         start of group #2 - first level TLD checking
       \\.[A-Za-z0-9]+  #           follow by a dot "." and string in the bracket [ ], must contains one or more (+)
      )*  #         end of group #2, this group is optional (*)
      (   #         start of group #3 - second level TLD checking
       \\.[A-Za-z]{2,}  #           follow by a dot "." and string in the bracket [ ], with minimum length of 2
      )   #         end of group #3
$   #end of the line

The combination means, email address must start with “_A-Za-z0-9-\\+” , optional follow by “.[_A-Za-z0-9-]”, and end with a “@” symbol. The email’s domain name must start with “A-Za-z0-9-“, follow by first level Tld (.com, .net) “.[A-Za-z0-9]” and optional follow by a second level Tld (.com.au, .com.my) “\\.[A-Za-z]{2,}”, where second level Tld must start with a dot “.” and length must equal or more than 2 characters.

1. Java Regular Expression Example

Here’s a Java example to show you how to use regex to validate email address.

EmailValidator.java

package com.javaSchool.regex;
 
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class EmailValidator {
 
 private Pattern pattern;
 private Matcher matcher;
 
 private static final String EMAIL_PATTERN = 
  "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@"
  + "[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
 
 public EmailValidator() {
  pattern = Pattern.compile(EMAIL_PATTERN);
 }
 
 /**
  * Validate hex with regular expression
  * 
  * @param hex
  *            hex for validation
  * @return true valid hex, false invalid hex
  */
 public boolean validate(final String hex) {
 
  matcher = pattern.matcher(hex);
  return matcher.matches();
 
 }
}

2. Valid Emails

1. javaSchool@yahoo.com, javaSchool-100@yahoo.com, javaSchool.100@yahoo.com
2. javaSchool111@javaSchool.com, javaSchool-100@javaSchool.net, javaSchool.100@javaSchool.com.au
3. javaSchool@1.com, javaSchool@gmail.com.com
4. javaSchool+100@gmail.com, javaSchool-100@yahoo-test.com

3. Invalid Emails

1. javaSchool – must contains “@” symbol
2. javaSchool@.com.my – tld can not start with dot “.”
3. javaSchool123@gmail.a – “.a” is not a valid tld, last tld must contains at least two characters
4. javaSchool123@.com – tld can not start with dot “.”
5. javaSchool123@.com.com – tld can not start with dot “.”
6. .javaSchool@javaSchool.com – email’s first character can not start with dot “.”
7. javaSchool()*@gmail.com – email’s is only allow character, digit, underscore and dash
8. javaSchool@%*.com – email’s tld is only allow character and digit
9. javaSchool..2002@gmail.com – double dots “.” are not allow
10. javaSchool.@gmail.com – email’s last character can not end with dot “.”
11. javaSchool@javaSchool@gmail.com – double “@” is not allow
12. javaSchool@gmail.com.1a -email’s tld which has two characters can not contains digit

4. Unit Test

EmailValidatorTest.java

package com.javaSchool.regex;
 
import org.testng.Assert;
import org.testng.annotations.*;
 
/**
 * Email validator Testing
 * 
 * @author javaSchool
 * 
 */
public class EmailValidatorTest {
 
 private EmailValidator emailValidator;
 
 @BeforeClass
 public void initData() {
  emailValidator = new EmailValidator();
 }
 
 @DataProvider
 public Object[][] ValidEmailProvider() {
  return new Object[][] { { new String[] { "javaSchool@yahoo.com",
   "javaSchool-100@yahoo.com", "javaSchool.100@yahoo.com",
   "javaSchool111@javaSchool.com", "javaSchool-100@javaSchool.net",
   "javaSchool.100@javaSchool.com.au", "javaSchool@1.com",
   "javaSchool@gmail.com.com", "javaSchool+100@gmail.com",
   "javaSchool-100@yahoo-test.com" } } };
 }
 
 @DataProvider
 public Object[][] InvalidEmailProvider() {
  return new Object[][] { { new String[] { "javaSchool", "javaSchool@.com.my",
   "javaSchool123@gmail.a", "javaSchool123@.com", "javaSchool123@.com.com",
   ".javaSchool@javaSchool.com", "javaSchool()*@gmail.com", "javaSchool@%*.com",
   "javaSchool..2002@gmail.com", "javaSchool.@gmail.com",
   "javaSchool@javaSchool@gmail.com", "javaSchool@gmail.com.1a" } } };
 }
 
 @Test(dataProvider = "ValidEmailProvider")
 public void ValidEmailTest(String[] Email) {
 
  for (String temp : Email) {
   boolean valid = emailValidator.validate(temp);
   System.out.println("Email is valid : " + temp + " , " + valid);
   Assert.assertEquals(valid, true);
  }
 
 }
 
 @Test(dataProvider = "InvalidEmailProvider", dependsOnMethods = "ValidEmailTest")
 public void InValidEmailTest(String[] Email) {
 
  for (String temp : Email) {
   boolean valid = emailValidator.validate(temp);
   System.out.println("Email is valid : " + temp + " , " + valid);
   Assert.assertEquals(valid, false);
  }
 }
}

Here’s the unit test result.

Email is valid : javaSchool@yahoo.com , true
Email is valid : javaSchool-100@yahoo.com , true
Email is valid : javaSchool.100@yahoo.com , true
Email is valid : javaSchool111@javaSchool.com , true
Email is valid : javaSchool-100@javaSchool.net , true
Email is valid : javaSchool.100@javaSchool.com.au , true
Email is valid : javaSchool@1.com , true
Email is valid : javaSchool@gmail.com.com , true
Email is valid : javaSchool+100@gmail.com , true
Email is valid : javaSchool-100@yahoo-test.com , true
Email is valid : javaSchool , false
Email is valid : javaSchool@.com.my , false
Email is valid : javaSchool123@gmail.a , false
Email is valid : javaSchool123@.com , false
Email is valid : javaSchool123@.com.com , false
Email is valid : .javaSchool@javaSchool.com , false
Email is valid : javaSchool()*@gmail.com , false
Email is valid : javaSchool@%*.com , false
Email is valid : javaSchool..2002@gmail.com , false
Email is valid : javaSchool.@gmail.com , false
Email is valid : javaSchool@javaSchool@gmail.com , false
Email is valid : javaSchool@gmail.com.1a , false
PASSED: ValidEmailTest([Ljava.lang.String;@15f48262)
PASSED: InValidEmailTest([Ljava.lang.String;@789934d4)
 
===============================================
    Default test
    Tests run: 2, Failures: 0, Skips: 0
===============================================

JAVA SCHOOL