Email regex Java

Email regex Java

The regular expressions below can be used to validate if a string is an email address and to extract email addresses from a string. This validation method however does not guarantee that the emails validated and extracted actually exist.

JavaScript
JavaScript
Python
Python
Java
Java
C#
C#
PHP
PHP

The basic validation

A simple Java regex to validate string against email format and catch the most obvious syntax errors:

Pattern.compile("^\\S+@\\S+\\.\\S+$")

Test it!
/^\S+@\S+\.\S+$/

True

False

Enter a text in the input above to see the result

Example code in Java:

import java.util.regex.Pattern;
import java.util.regex.MatchResult;

public class Main {

    public static void main(String []args) {
        // Validate if a string is a email 
        boolean isMatch = Pattern.compile("^\\S+@\\S+\\.\\S+$")
               .matcher("hello@uibakery.io")
               .find(); // returns true
        
        // Extract emails from a string
        String[] matches = Pattern.compile("\\S+@\\S+\\.\\S+")
                          .matcher("You can reach me out at hello@uibakery.io and contact@uibakery.io")
                          .results()
                          .map(MatchResult::group)
                          .toArray(String[]::new); // returns ["hello@uibakery.io", "contact@uibakery.io"]
    }
}

The more complex email regex

This Java regular expression will match 99% of valid email addresses and will not pass validation for email addresses that have, for instance:

  • Dots in the beginning
  • Multiple dots at the end

But at the same time it will allow part after @ to be IP address.

Pattern.compile("^[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$")

Test it!
/^[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/

True

False

Enter a text in the input above to see the result

Example code in Java:

import java.util.regex.Pattern;

public class Main {

     public static void main(String []args) {
        // Validate if a string is a email 
        Pattern validateEmailPattern = Pattern.compile("^[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$");
        validateEmailPattern.matcher("hello@uibakery.io.").find(); // returns false
        validateEmailPattern.matcher("hello@192.168.0.1").find(); // returns true
     }
}

RFC 5322 compliant regex

This Java regular expression is compliant to RFC 5322 standard which allows for the most complete validation. Usually, you should not use it because it is an overkill. In most cases apps are not able to handle all emails that this regex allows.

Pattern.compile("(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])")

Test it!
/(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])/

True

False

Enter a text in the input above to see the result

Example code in Java:

import java.util.regex.Pattern;
import java.util.regex.MatchResult;

public class Main {

     public static void main(String []args) {
        // Validate if a string is a email 
        Pattern validateEmailPattern = Pattern.compile("(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])");
        validateEmailPattern.matcher("hello@uibakery.io").find(); // returns true
     }
}

Extra information about validating email

As was stated previously, Java regex email validation can not fully guarantee that email exists and the message can be delivered. The best way how to know for sure that email is valid is to actually send an email to that address because even paid email validation services do not provide a 100% guarantee for that.