/** Contructor */
  Application() {
    // inicalizes the lists
    users = new PersonList("Pessoas.dat", Person.PersonTypes.USER);
    techs = new PersonList("Pessoas.dat", Person.PersonTypes.WORKER);
    posts = new StationList("Postos_trab.dat");

    tickets = new TicketList("Pedidos.txt", "Intervencoes.txt", users, techs, posts);

    // loads files
    posts.loadFile();
    users.loadFile();
    techs.loadFile();
    tickets.loadFile();
  }
  /** exit's the application */
  public void exit() {
    // saves posts
    posts.saveFile();

    // saves users and techs in one file
    PersonList pl = new PersonList("Pessoas.dat", Person.PersonTypes.ALL);

    for (int i = 0; i < users.size(); i++) pl.add(users.get(i));
    for (int i = 0; i < techs.size(); i++) pl.add(techs.get(i));
    pl.saveFile();

    tickets.saveFile();

    System.exit(0);
  }