Question about Regex Parsing in Java

[Shawn Smith]

I'm attempting to determine valid email address formation using regex and failing. I've tested the same regex against the C regcomp and regexex, and boost's c++ regex libraries with consistent (and correct results). The java code fails to match on anything though. Any insight into the differences in processing would be greatly appreciated.

The matching code:

public static boolean isValidEmailAddr(String addr)
  {
    if(validEmailAddressRegex_  == null)
      loadValidationFields();

    //((^|@)[[:alnum:]!#$%&'*+/=?^_`{|}~-]+(\\.[[:alnum:]!#$%&'*+/=?^_`{|}~-]+)*){2}$
    Pattern p = Pattern.compile(validEmailAddressRegex_);
    Matcher m = p.matcher(addr);

    return m.matches();
  }

The test code:

 public class Test
{
  public static void main(String [] args)
  {
    System.out.print("123@fda@hello - ");
    if (ValidationUtil.isValidEmailAddr("123@fda@hello"))
      System.out.println("Valid");
    else
      System.out.println("invalid");

    System.out.print("[e-mail] - ");
    if (ValidationUtil.isValidEmailAddr("[e-mail]"))
      System.out.println("Valid");
    else
      System.out.println("invalid");

    System.out.print("hello - ");
    if (ValidationUtil.isValidEmailAddr("hello"))
      System.out.println("Valid");
    else
      System.out.println("invalid");

    System.out.print("@hello - ");
    if (ValidationUtil.isValidEmailAddr("@hello"))
      System.out.println("Valid");
    else
      System.out.println("invalid");

    System.out.print("hello@ - ");
    if (ValidationUtil.isValidEmailAddr("hello@"))
      System.out.println("Valid");
    else
      System.out.println("invalid");

    System.out.print("[e-mail] - ");
    if (ValidationUtil.isValidEmailAddr("[e-mail]"))
      System.out.println("Valid");
    else
      System.out.println("invalid");
  }
}

I'm expecting [email protected] and [email protected] to match.

Cheers,
Shawn

[Jeff Verdegan]

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

And if that doesn't answer your question, I'm sure you can get plenty of help by googling for something like java email regex.

Also note that you probably don't want a regex that perfectly matches the RFC for email addresses, for reasons spelled out in the regular-expressions.info link, and if you choose to do so, it will be a horrendous regex.

[Jeff Verdegan]

Note also that for POSIX character classes, Java uses \p{class}, not [:class:], which is spelled out in the docs for java.util.regex.Pattern, so \p{Alnum}, which of course becomes

"\\p{Alnum}"

if you're using a Java String literal to specify the pattern.

Always worth reading the docs before posting to a forum.

[Shawn Smith]

Jeff Verdegan wrote:Note also that for POSIX character classes, Java uses \p{class}, not [:class:], which is spelled out in the docs for java.util.regex.Pattern. Always worth reading before posting to a forum.

Thanks much. I actually had read it and just figured out that Properties was stealing my escape for the \p{class} which had me chasing my tail.

Thanks again for the feedback.

[Jeff Verdegan]

Cool. Gald you got it!