Programación java

package com.mkyong.common;
 
import java.util.Properties;
 
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
 public class SendMailTLS {
 
 public static void main(String[] args) {
   final String username = "user@gmail.com";
  final String password = "pass";
   Properties props = new Properties();
  props.put("mail.smtp.auth", "true");
  props.put("mail.smtp.starttls.enable", "true");
  props.put("mail.smtp.host", "smtp.gmail.com");
  props.put("mail.smtp.port", "587");
   Session session = Session.getInstance(props,
    new javax.mail.Authenticator() {
  protected PasswordAuthentication getPasswordAuthentication() {
   return new PasswordAuthentication(username, password);
   }
    });
   try {
   Message message = new MimeMessage(session);
  message.setFrom(new InternetAddress("from@gmail.com"));
  message.setRecipients(Message.RecipientType.TO,
    InternetAddress.parse("to@gmail.com"));
  message.setSubject("Subject");
  message.setText("email de prueba");
    Transport.send(message);
    System.out.println("Finalizado");
   } catch (MessagingException e) {
   throw new RuntimeException(e);
  }
 }
}