update_polling.java

int latestUpdateCount = ... // Persist this value

// Each time you want to check for new and updated notes...
SyncState currentState = noteStore.getSyncState();
int currentUpdateCount = currentState.getUpdateCount();

if (currentUpdateCount > latestUpdateCount) {

  // Something in the account has changed, so search for notes
  NotesMetadataList newNotes = noteStore.findNotesMetadata( ... );
  
  // Do something with the notes you found...
  for (NoteMetadata note : newNotes.getNotes()) {
    // ...
  }
  
  // Keep track of the new high-water mark
  latestUpdateCount = currentSyncState.getUpdateCount();
}