Mail.java

public class Mail {
    public void doSendMails() {
        //Creating ArrayList of the ThreadClass to hold reference of the threads
        ArrayList<ThreadClass> mailManThreads = new ArrayList();
        for (int cnt = 0; cnt < mailManThreads.size(); cnt++) {
            Vector oneMailQueue = new Vector();
            oneMailQueue = allMails.get(cnt);
            ThreadClass oneMailManThread = new ThreadClass();
            oneMailManThread.start(oneMailQueue);
            mailManThreads.add(oneDealerThread);
        }
        // Joins all threads to main thread to avoid main thread to continue without finishing the rest of threads
        for (int cnt = 0; cnt < mailManThreads.size(); cnt++) {
            mailManThreads.get(cnt).join();
        }
    }
}