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How to validate an Email Address with plain Java?

Hi,
I have some records that I am storing in a bean like class.
email address is one of the variable within this class.
I want to have a method that takes a string (the email) and validates the email address.
Need some logic to validate the email address...
Thanks.
_Esam
0
_Esam
Asked:
_Esam
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1 Solution
 
StillUnAwareCommented:
Some possible solutions:

      //Input the string for validation
      String email = "xyz@hotmail.com";

      //Set the email pattern string
      Pattern p = Pattern.compile(".+@.+\\.[a-z]+");

      //Match the given string with the pattern
      Matcher m = p.matcher(email);

      //check whether match is found
      boolean matchFound = m.matches();

      if (matchFound)
        System.out.println("Valid Email Id.");
      else
        System.out.println("Invalid Email Id.");
from (http://www.devx.com/tips/Tip/28334)

/*
* Checks for invalid characters
* in email addresses
*/
public class EmailValidation {
   public static void main(String[] args)
                                 throws Exception {
                                 
      String input = "@sun.com";
      //Checks for email addresses starting with
      //inappropriate symbols like dots or @ signs.
      Pattern p = Pattern.compile("^\\.|^\\@");
      Matcher m = p.matcher(input);
      if (m.find())
         System.err.println("Email addresses don't start" +
                            " with dots or @ signs.");
      //Checks for email addresses that start with
      //www. and prints a message if it does.
      p = Pattern.compile("^www\\.");
      m = p.matcher(input);
      if (m.find()) {
        System.out.println("Email addresses don't start" +
                " with \"www.\", only web pages do.");
      }
      p = Pattern.compile("[^A-Za-z0-9\\.\\@_\\-~#]+");
      m = p.matcher(input);
      StringBuffer sb = new StringBuffer();
      boolean result = m.find();
      boolean deletedIllegalChars = false;

      while(result) {
         deletedIllegalChars = true;
         m.appendReplacement(sb, "");
         result = m.find();
      }

      // Add the last segment of input to the new String
      m.appendTail(sb);

      input = sb.toString();

      if (deletedIllegalChars) {
         System.out.println("It contained incorrect characters" +
                           " , such as spaces or commas.");
      }
   }
}

from (http://java.sun.com/developer/technicalArticles/releases/1.4regex/)
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StillUnAwareCommented:
This looks promissing:

"^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)*$"

it provides somewhat more accurate regex expression
from (http://www.h2co3.com/blog/archives/000013.html)
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Mayank SAssociate Director - Product EngineeringCommented:
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StillUnAwareCommented:
> http://www.devx.com/tips/Tip/28334

Already posted that :)
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Mayank SAssociate Director - Product EngineeringCommented:
Sorry I didn't realize there was link in between that long code sample.
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_EsamAuthor Commented:
NOW..
> "^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)*$"

Should this be enough to validate an email address/

_Esam
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_EsamAuthor Commented:
Is this a valid email address: "a@com"  ?
This > "^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)*$"
returns this email address as valid???

_Esam
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Mayank SAssociate Director - Product EngineeringCommented:
>> a@com

No.
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StillUnAwareCommented:
Instead of

"^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)*$"

use this

"^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)+$"
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_EsamAuthor Commented:
>"^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)+$"

I personally don't think that this is enough :)
What do you say???
_Esam....
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_EsamAuthor Commented:
Is this ok: "m-.a@com.m.m.m" ?

_Esam.
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Mayank SAssociate Director - Product EngineeringCommented:
>> m-.a@com.m.m.m

Yes that looks ok.
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_EsamAuthor Commented:
I have the method as:

public static boolean isValidEmailAddress(String email)
    {
        String regex = "^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)+$" ;
        return email.matches(regex);
    }

Now, I looked at this link: http://java.sun.com/developer/technicalArticles/releases/1.4regex/

And I think I should include some other conditions too....

Not quite sure how to do that...
I want to test the email for all the conditions and then return if true...

How?

Thanks.
_Esam...
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StillUnAwareCommented:
It won't give You any better results. The regex You are using is one of many solutions, here is another one
(from http://www.houseoffusion.com/cf_lists/messages.cfm/forumid:21/threadid:149):

^[_a-zA-Z0-9-]+(\\.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(\\.[a-zA-Z0-9-]+)*\\.(([0-9]{ 1,3})|([a-zA-Z]{2,6})

The last one is a little bit more restrictive and accurate, but still not perfect, cause it's not possible to be sure if the text You are reading is some 'text', email address or simply trash.

To be convinced on that, try for example use OutlookExpress, add some news group and try to open a message with partial file attachment. The OutlookExpress starts to filter the binary data for links, which results in heavy time consuming and meaningless task.
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_EsamAuthor Commented:
>>   ^[_a-zA-Z0-9-]+(\\.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(\\.[a-zA-Z0-9-]+)*\\.(([0-9]   (here) { 1,3})|([a-zA-Z]{2,6})

It gave me some error here --- the white space  

The error: (the by ^)
java.util.regex.PatternSyntaxException: Illegal repetition near index 74
^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.(([0-9]     ^         { 1,3})|([a-zA-Z]{2,6})

Let me know..
Thanks.
_Esam
   
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_EsamAuthor Commented:
Hello....  StillUnAware or mayankeagle

What's wrong with the expression... some syntax error...
Can you figure out..
I can't see it...


Thanks.
_Esam.
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StillUnAwareCommented:
Sorry for that, I did a quick copy and edit and missed some last characters. It should be:

"^[_a-zA-Z0-9-]+(\\.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(\\.[a-zA-Z0-9-]+)*\\.(([0-9]{1,3})|([a-zA-Z]{2,6}))$"
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StillUnAwareCommented:
Also, to get a grip on regular expressions may be usefull for future tasks, You should consider reading a bit more about it, at least to understand what does the supplied expressions means. Some info:

http://java.sun.com/docs/books/tutorial/extra/regex/index.html
http://java.sun.com/j2se/1.5.0/docs/api/java/util/regex/Pattern.html
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_EsamAuthor Commented:
Excellent .. thanks..
I will look onto the useful links you provided...

Thanks much,...

_Esam.
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