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Getting NPE when getting sender's omemo device in OmemoService for MUC

Question asked by Vishnu Prajapati on Aug 1, 2017
Latest reply on Aug 1, 2017 by Vishnu Prajapati



I'm working on Omemo encryption for MUC with smack 4.2.1-SNAPSHOT. When user is receiving messages from muc, it is giving entity full jid nil of sender which cause NPE in MultiUserChat for getting occupant of muc.

private static OmemoDevice getSender(OmemoManager omemoManager, Stanza stanza) {


  OmemoElement omemoElement = (OmemoElement)stanza.getExtension("encrypted", "eu.siacs.conversations.axolotl");

  BareJid sender = stanza.getFrom().asBareJid();   /* I think, instead of using BareJid of sender we can use Jid which would easily be converted into EntityFullJid or                                                                                               EntityBareJid. */

  if(isMucMessage(omemoManager, stanza)) {

    MultiUserChatManager mucm = MultiUserChatManager.getInstanceFor(omemoManager.getConnection());

    MultiUserChat muc = mucm.getMultiUserChat(sender.asEntityBareJidIfPossible());

    sender = muc.getOccupant(sender.asEntityFullJidIfPossible()).getJid().asBareJid();    /* Getting entityFullJid null */



   if(sender == null) {

   throw new AssertionError("Sender is null.");

  } else {

   return new OmemoDevice(sender, omemoElement.getHeader().getSid());





Exception in async packet listener

java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.Object.hashCode()' on a null object reference

     at java.util.concurrent.ConcurrentHashMap.get(

     at org.jivesoftware.smackx.muc.MultiUserChat.getOccupantPresence(MultiUserChat.jav a:1667)

     at org.jivesoftware.smackx.muc.MultiUserChat.getOccupant(