Question

Note: My current solution is working (I think). I just want to make sure I’m not missing anything.

My question: I’m wondering how to check whether an exception was caused because an invalid e-mail address. Using Java Mail.

Currently I’m checking SMTPAddressFailedExceptions with getAddress() and AddressExceptions with getRef().

Here’s my current method for conducting the check. Am I missing anything?

/**
* Checks to find an invalid address error in the given exception. Any found will be added to the ErrorController's
* list of invalid addresses. If an exception is found which does not contain an invalid address, returns false.
*
* @param exception the MessagingException which could possibly hold the invalid address
* @return if the exception is not an invalid address exception.
*/
public boolean handleEmailException(Throwable exception) {
  String invalidAddress;
  do {
    if (exception instanceof SMTPAddressFailedException) {
      SMTPAddressFailedException smtpAddressFailedException = (SMTPAddressFailedException) exception;
      InternetAddress internetAddress = smtpAddressFailedException.getAddress();
      invalidAddress = internetAddress.getAddress();
    } else if (exception instanceof AddressException) {
      AddressException addressException = (AddressException) exception;
      invalidAddress = addressException.getRef();
    }
    //Here is where I might do a few more else ifs if there are any other applicable exceptions.
    else {
      return false;
    }
    if (invalidAddress != null) {
      //Here's where I do something with the invalid address.
    }
    exception = exception.getCause();
  } while (exception != null);
  return true;
}

---

Note: In case you’re curious (or it’s helpful), I use the Java Helper Library to send the e-mail (see this line) so that’s where the error is thrown initially.

Answer 1

You shouldn’t usually need to cast exceptions; that’s why you can have multiple catch blocks:

try {
    // code that might throw AddressException
} catch (SMTPAddressFailedException ex) {
    // Catch subclass of AddressException  first
    //  ...
} catch (AddressException ex) {
    // ...
}

If you are worried about nested exceptions, you can use Guava’s Throwables.getRootCause.