"Observer" pattern for this use case

Question

I have a DAO class that has a method to save in db everytime something in my object changes. When this save happens, i want to kick start another flow that publishes to a SNS topic that an update has happened. I dont believe below is the right approach as these are two seperate tasks and this will just increase the latency of the saveInDB method.

class DAO {
    SNSPublish publishToSNS;
    DynamoDB dynamoDbMapper;

   public void saveinDB(final myObj obj) {
       dynamoDbMapper.save(obj);
       publishToSNS.publish(obj);
   }

I would like to keep the publish part as a separate atomic event, so was wondering what is the easiest way to create an observer in java, that every time a save to DB happens will notify the SNSPublish class to do the publish rather than doing this serially.