Printing variable values in Java

Question

I've got an object which is a new MimeMessage called message and I want to find out what it's passing to my outgoing mail server. I however have no idea how one gets a variable like this printed out in Java. Here's some code:

private String sendConfirmationEmail (String to, String from, String subject, String body, boolean CCSender) {
      try
      {
  //            String smtpHost = Properties.smtp;
          String smtpHost = Properties.smtp;      
          String fromAddress = from;
          String toAddress = to;

          Properties properties = System.getProperties();
          properties.put("mail.smtp.host", smtpHost);

          Session session = Session.getInstance(properties, null);

          MimeMessage message = new MimeMessage(session);

          message.setFrom(new InternetAddress(fromAddress));
          message.setRecipient(Message.RecipientType.TO,
                  new InternetAddress(toAddress));

          if (CCSender) {
            message.setRecipient(Message.RecipientType.CC,
                    new InternetAddress(from));
          }
          message.setSubject(subject);
          message.setText(body);

          System.out.println(message); <=== I want this to work!

          message.saveChanges();
          Transport.send(message);
          return "1:success";
      }
      catch(Exception e)
      {
          return "0:failure "+e.toString();
      }
  }

Any help would be much appreciated.

Thanks.

Answer 1

For MimeMessage, you can call message.writeTo(System.out);. You will probably want to do this after calling message.saveChanges() to ensure consistency.

Answer 2

If it's a class you have control of, you override it's toString() method

If you have no control over it, you'll have to write a method like

String valueOf(Message message) {
    StringBuilder sb = new StringBuilder();
    sb.append(message.someValue());
    sb.append(message.someOtherValue());
    return sb.toString();
}

and use valueOf in your debug message

For MimeMessage, I'd rely on it having a toString implementation for its content

String valueOf(Message message) {
    return message.getContent().toString();
}

Answer 3

You could create a decorator class implementing the base interface, and logging/printing everything returned by the wrapped class' toString() (or whatever other methods the base interface has).