private boolean haveShownMessageBefore(UpdateMessage msg){
  if (!msg.isShownOnce())   return false;
  loadSeenMessages();
  if (_seenMessages == null || _seenMessages.size() == 0 || !_seenMessages.contains(msg)) {
    if (_seenMessages == null)     _seenMessages=new HashSet<>();
    _seenMessages.add(msg);
    saveSeenMessages();
    return false;
  }
  return true;
}

private boolean haveShownMessageBefore ( UpdateMessage msg ) { if ( ! msg . isShownOnce ( ) ) return false ; loadSeenMessages ( ) ; if ( _seenMessages == null || _seenMessages . size ( ) == 0 || ! _seenMessages . contains ( msg ) ) { if ( _seenMessages == null ) _seenMessages = new HashSet < > ( ) ; _seenMessages . add ( msg ) ; saveSeenMessages ( ) ; return false ; } return true ; }
checks on a message map , if we ' ve seen this message before . the message map is serialized on disk every time we write to it . its initialized from disk when we start the update manager .
