Validate email id with regular expression

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.mkyong.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. javatyro@yahoo.com, javatyro-100@yahoo.com, javatyro.100@yahoo.com
2. javatyro111@javatyro.com, javatyro-100@javatyro.net, javatyro.100@javatyro.com.au
3. javatyro@1.com, javatyro@gmail.com.com
4. javatyro+100@gmail.com, javatyro-100@yahoo-test.com
3. Invalid Emails

1. javatyro – must contains “@” symbol
2. javatyro@.com.my – tld can not start with dot “.”
3. javatyro123@gmail.a – “.a” is not a valid tld, last tld must contains at least two characters
4. javatyro123@.com – tld can not start with dot “.”
5. javatyro123@.com.com – tld can not start with dot “.”
6. .javatyro@javatyro.com – email’s first character can not start with dot “.”
7. javatyro()*@gmail.com – email’s is only allow character, digit, underscore and dash
8. javatyro@%*.com – email’s tld is only allow character and digit
9. javatyro..2002@gmail.com – double dots “.” are not allow
10. javatyro.@gmail.com – email’s last character can not end with dot “.”
11. javatyro@javatyro@gmail.com – double “@” is not allow
12. javatyro@gmail.com.1a -email’s tld which has two characters can not contains digit

4. Unit Test

Here’s a unit test using testNG.

EmailValidatorTest.java

package com.javatyro.regex;



import org.testng.Assert;

import org.testng.annotations.*;



/**

 * Email validator Testing

 * 

 * @author javatyro

 * 

 */

public class EmailValidatorTest {



    private EmailValidator emailValidator;



    @BeforeClass

    public void initData() {

        emailValidator = new EmailValidator();

    }



    @DataProvider

    public Object[][] ValidEmailProvider() {

        return new Object[][] { { new String[] { "javatyro@yahoo.com",

            "javatyro-100@yahoo.com", "javatyro.100@yahoo.com",

            "javatyro111@javatyro.com", "javatyro-100@javatyro.net",

            "javatyro.100@javatyro.com.au", "javatyro@1.com",

            "javatyro@gmail.com.com", "javatyro+100@gmail.com",

            "javatyro-100@yahoo-test.com" } } };

    }



    @DataProvider

    public Object[][] InvalidEmailProvider() {

        return new Object[][] { { new String[] { "javatyro", "javatyro@.com.my",

            "javatyro123@gmail.a", "javatyro123@.com", "javatyro123@.com.com",

            ".javatyro@javatyro.com", "javatyro()*@gmail.com", "javatyro@%*.com",

            "javatyro..2002@gmail.com", "javatyro.@gmail.com",

            "javatyro@javatyro@gmail.com", "javatyro@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 : javatyro@yahoo.com , true

Email is valid : javatyro-100@yahoo.com , true

Email is valid : javatyro.100@yahoo.com , true

Email is valid : javatyro111@javatyro.com , true

Email is valid : javatyro-100@javatyro.net , true

Email is valid : javatyro.100@javatyro.com.au , true

Email is valid : javatyro@1.com , true

Email is valid : javatyro@gmail.com.com , true

Email is valid : javatyro+100@gmail.com , true

Email is valid : javatyro-100@yahoo-test.com , true

Email is valid : javatyro , false

Email is valid : javatyro@.com.my , false

Email is valid : javatyro123@gmail.a , false

Email is valid : javatyro123@.com , false

Email is valid : javatyro123@.com.com , false

Email is valid : .javatyro@javatyro.com , false

Email is valid : javatyro()*@gmail.com , false

Email is valid : javatyro@%*.com , false

Email is valid : javatyro..2002@gmail.com , false

Email is valid : javatyro.@gmail.com , false

Email is valid : javatyro@javatyro@gmail.com , false

Email is valid : javatyro@gmail.com.1a , false

PASSED: ValidEmailTest([Ljava.lang.String;@15f48262)

PASSED: InValidEmailTest([Ljava.lang.String;@789934d4)



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    Default test

    Tests run: 2, Failures: 0, Skips: 0

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