public boolean changeRoom(String user, String room){
        UserAccount account = users.get(user.toLowerCase());
        ChatServerChatRoom room2 = chatRooms.get(room);
        if (account==null || room2 ==null) return false;
        ChatServerThread thread = account.getThread();
        if (thread==null) return false;
        thread.getRoom().removeThread(thread);
        room2.addThread(thread);
        thread.setRoom(room2);
        System.out.println(""+user+" changed to room "+room);
        return true;
    }