Java Email Folder check email from Gmail server

import java.util.Arrays;
import java.util.Properties;

import javax.mail.Address;
import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.internet.InternetAddress;

public class Main {
   volatile boolean shouldContinue = true;
   Thread mailCheckingThread = null;

   public static void main(String[] args) {
      new Main().start();
   }//from ww  w  .j  a va2s . co  m

   public void start() {
      mailCheckingThread = new Thread(new Runnable() {
         @Override
         public void run() {
            while (shouldContinue) {
               checkForMail();
               try {
                  Thread.sleep(5000);
               } catch (InterruptedException e) {
                  e.printStackTrace();
               }
            }
         }
      });
      mailCheckingThread.start();
   }

   public void stop() {
      shouldContinue = false;
      mailCheckingThread.interrupt();
      try {
         mailCheckingThread.join();
      } catch (InterruptedException e) {
         e.printStackTrace();
      }
   }

   private void checkForMail() {
      Properties properties = new Properties();
      String username = "test";
      String password = "password";
      String folder = "Inbox";
      String host = "imap.gmail.com";

      try {
         Session session = Session.getDefaultInstance(properties, null);
         Store store = session.getStore("imaps");
         store.connect(host, username, password);
         Folder inbox = store.getFolder(folder);
         inbox.open(Folder.READ_WRITE);
         int messageCount = inbox.getMessageCount();
         Message messages[] = inbox.getMessages(1, messageCount);
         for (Message message : messages) {
            if (Arrays.asList(message.getFlags().getSystemFlags()).contains(Flags.Flag.SEEN)) {
               continue; // not interested in "seen" messages
            }
            if (processMessage(message)) {
               System.out.println("Processed :" + message.getSubject());
               message.setFlag(Flags.Flag.DELETED, true);
            } else {
               System.out.println("Couldn't Understand :" + message.getSubject());
               // set it as seen, but keep it around
               message.setFlag(Flags.Flag.SEEN, true);
            }
         }
         inbox.close(true);
      } catch (MessagingException e) {
         e.printStackTrace();
      }
   }

   private boolean processMessage(Message message) throws MessagingException {
      boolean result = false;

      String subject = message.getSubject().toLowerCase();
      if (subject.startsWith("subscribe")) {
         String emailAddress = extractEmail(message.getFrom());
         if (emailAddress != null) {
            subscribeToList(emailAddress);
            result = true;
         }

      } else if (subject.startsWith("unsubscribe")) {
         String emailAddress = extractEmail(message.getFrom());
         if (emailAddress != null) {
            unSubscribeToList(emailAddress);
            result = true;
         }
      }

      return result;
   }

   private String extractEmail(Address[] addressArray) {
      if ((addressArray == null) || (addressArray.length < 1))
         return null;
      if (!(addressArray[0] instanceof InternetAddress))
         return null;
      InternetAddress internetAddress = (InternetAddress) addressArray[0];
      return internetAddress.getAddress();
   }

   private void subscribeToList(String address) {
      System.out.println("Subscribing for :" + address);
   }

   private void unSubscribeToList(String address) {
      System.out.println("UNsubscribing for :" + address);
   }

}