public void addList (String name)
    {
        boolean jump = true;
        for ( int i = usernames.size() - 1; i >= 0; i--)
        {
            if (usernames.get(i).equals(name))
            {
                jump = false;
            }
        }
        if (jump)
        {
            usernames.add(name);
            model.addElement(name);
        }
    }