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How do I accept a valid email id in a textbox?

I have developed a chat application using servlets and jsp. I have developed a user login page where I accept the used id and its mail -id. How can I make sure the user has typed in the correct mail id. I need a code to validate the email name. I mean, for example, the user cannot enter anything in the textbox.

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5 answers


You need to verify the authenticity of your email. The easiest way is to use regex: there is information here . This will of course be client-side when you validate your form.



If you are using hibernate bean validation, there is an annotation @Email

that you can use as well.

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Apache Commons EmailValidator

does this if you are doing server side validation. If you are worried about client side validation, you need to create a regex and match it using JavaScript.



EmailValidator validator = EmailValidator.getInstance();
if (validator.isValid(yourEmail)) {
    // valid e-mail
} else {
    // invalid e-mail
}
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You need to make sure the provided value is passing a regular expression for a valid email address.

More details: http://www.regular-expressions.info/email.html

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Here's the simplest implementation of the general concept of other posters described using JavaScript:

function isValidEmail(str) {
   return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
}

(from http://www.codetoad.com/javascript/is_valid_email.asp )

Using regex to validate email address in Java:

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();
      }
}

(from http://www.mkyong.com/regular-expressions/how-to-validate-email-address-with-regular-expression/ )

Each link was either # 1 or # 2 in Google search.

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Most of the current regex regex validators do not account for that in characters . Everyone needs to change the regular expression used by e-mail, because these characters are, of course, will not be covered [a-z]/i

and \w

the usual solution of regex. They will all fail.

In the end, the best way to verify an email address is still to send an email to the specified address to verify the address. An end user can, for example, enter a syntactically valid emailaddress, for example w40ejk5gdf8sg@xl5er8kw8tklt.com

, but which obviously does not exist. If the email address is part of the user authentication (register / login / etc), you can ideally combine it with a user activation system. That is, send an email with a link with a unique activation key to the specified email address and only allow registration when the user has activated the newly created account using the link in the email.

If the purpose of a regex is to simply inform the user in the user interface that the specified email address does not look in the correct format, it is best to check if it basically matches the following regex:

^([^.@]+)(\.[^.@]+)*@([^.@]+\.)+([^.@]+)$

Just. You don't need to worry about the characters used in the name and domain. After all, it is the customer's responsibility to enter a legitimate email address, not a server.

In Java, you can use the above expression as:

public static boolean isValidEmail(String value) {
    return value.matches("^([^.@]+)(\\.[^.@]+)*@([^.@]+\\.)+([^.@]+)$");
}
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