Final

public abstract class MenuEntry {

    private String title;
    public MenuEntry(String title) {
        this.title = title;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public abstract void run();
}


public class Menu {
    private static final String MENU_PATTERN = "%s - %s\n";
    private ArrayList<MenuEntry> entries = new ArrayList<MenuEntry>();
    private boolean isExit = false;

    public Menu() {
        entries.add(new MenuEntry("Exit") {
            @Override
            public void run() {
                isExit = true;
            }
        });
    }

    public void run() {
        Scanner sc = new Scanner(System.in);
        while (!isExit) {
            printMenu();

            try {
                String line = sc.nextLine();

                int choice = Integer.parseInt(line);
                MenuEntry entry = entries.get(choice - 1);
                entry.run();

            } catch (NumberFormatException e) {
                System.out.print("Wrong input!");
            } catch (IndexOutOfBoundsException e2) {
                System.out.print("Wrong input!");
            }
        }
        sc.close();
    }

    public Menu addEntry(MenuEntry entry) {
        int index = entries.size() - 1;
        entries.add(index, entry);
        return this;

    }

    private void printMenu() {
        StringBuffer buffer = new StringBuffer();
        buffer.append("\nMenu:\n");
        for (int i = 0; i < entries.size(); i++) {
            MenuEntry entry = entries.get(i);
            String entryFormatted = String.format(MENU_PATTERN, (i + 1), entry.getTitle());
            buffer.append(entryFormatted);
        }
        System.out.print(buffer.toString());
    }

}


public class MailSender {

    /**
     * @param args
     */

    final String userName = "marinajavatest@gmail.com";
    final String password = "javatest_5";

    Properties props = new Properties();

    public void setProperties() {
        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 javax.mail.PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(userName, password);
        }
    });

    public void sendMessage(String adress) {
        try {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(userName));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(adress));
            message.setSubject("Changes have been found");
            message.setText("File has been chaged");
            Transport.send(message);
            System.out.println("Done! Message has been sent to the e-mail" + "'" + adress + "'");
        } catch (AddressException ex) {
            System.out.println ("E-mail adress doesn't exsist");
        } catch (MessagingException ex) {
            System.out.println  ("Sorry...something was wrong. E-mail hasn't been sent");
        }
    }

}


public class File extends Thread {

    ArrayList<String> example;
    String name;
    String adress;

    File(String name, String adress) {
        this.name = name;
        this.adress = adress;
        this.example = new ArrayList<String>();
        this.setDaemon(true);
    }

    public static ArrayList<String> readFile(String name) throws FileNotFoundException {
        Scanner scanner = null;
        scanner = new Scanner(new BufferedReader(new FileReader(name)));
        ArrayList<String> fileList = new ArrayList<String>();
        while (scanner.hasNextLine()) {
        fileList.add(scanner.nextLine());
        }
        scanner.close();
        return fileList;
    }

    public static void sendMessage(String adress) {
        MailSender mailsender = new MailSender();
        mailsender.setProperties();
        mailsender.sendMessage(adress);
    }

    public void observeFiles() throws FileNotFoundException, InterruptedException {
        ArrayList<String> baseFile;
        ArrayList<String> observableFile;
        boolean b = true;
        while (b) {
            baseFile = File.readFile(name);
            Thread.sleep(5000);
            observableFile = File.readFile(name);
            if (!baseFile.equals(observableFile)) {
                System.out.println("Tracking for file " + name + " has been changed");
                File.sendMessage(adress);
                } else {
            System.out.println("There are no changes in the file");
            }
            baseFile.clear();
            baseFile.addAll(observableFile);
        }
    }

    public void run() {
        try {
            this.observeFiles();
        } catch (FileNotFoundException ex) {
            System.out.print("There are no files with such name!");
            return;
        } catch (InterruptedException ex) {
            System.out.print("For file " + name + " tracking has been stopped");
            return;
        }
    }

}
public class Test {
    public static void main(String[] args) {

        Menu menu = new Menu();
        ArrayList<File> fileCollection = new ArrayList<File>();
        Scanner sc = new Scanner(System.in);
        System.out.println(
                "Hi! Just try to track changes in the file non-stop. To start enter your e-mail adress to receive a notification about changes and then follow the menu!");
        System.out.println("Enter the e-mail");
        String emailAdress = sc.nextLine();
        menu.addEntry(new MenuEntry("Start tracking file") {
            @Override
            public void run() {

                System.out.print("Enter the file name" + "\n");
                String entry = sc.nextLine();
                File file = new File(entry, emailAdress);
                fileCollection.add(file);
                file.setName(entry);
                file.start();
            }
        });

        menu.addEntry(new MenuEntry("Stop tracking file") {

            public void run() {

                System.out.println("Enter the number: 1.Stop tracking for all files" + " "
                        + "2.Stop tracking for one file" + " " + "3.Cancel and return" + "\n");
                boolean b = true;
                boolean stop = false;
                while (b) {
                    try {
                        int input = sc.nextInt();
                        switch (input) {
                        case 1:
                            if (fileCollection.size() != 0) {
                                for (File s : fileCollection) {
                                    s.interrupt();
                                }
                                fileCollection.clear();
                            } else {
                                System.out.println("No active processes");
                            }
                            return;
                        case 2:
                            if (fileCollection.size() != 0) {
                                System.out.print("Number of active files: " + fileCollection.size() + "\n"
                                        + "They are: " + "\n");
                                for (File s : fileCollection) {
                                    System.out.println(s.getName());
                                }
                                System.out.println("Enter the number:");
                                int number = sc.nextInt();
                                while (!stop) {
                                    if (fileCollection.get(number - 1).isInterrupted()) {
                                    stop = true;
                                    }
                                    fileCollection.get(number - 1).interrupt();
                                    fileCollection.remove(number - 1);
                                }
                            } else {
                                System.out.println("No active processes");
                            }
                        case 3:
                            return;
                        default:
                            System.out.print("Wrong input!" + "\n");
                            break;
                        }
                    } catch (InputMismatchException ex) {
                        System.out.print("Wrong input!");
                    }
                }
            }
        });

        menu.run();
        sc.close();
    }
}