Android上的onDataChanged返回两次数据库更改值

Question

每次更新数据库中的值时，我都会观察到Activity中的更改。由于某种原因，更改被触发两次。一次使用旧值，一次使用新值。但是，它们不保留此顺序。就是说，有时候我首先获得旧价值，有时我首先获得新价值。

我在堆栈溢出时查找了问题，并遇到了启用持久性的问题。我也尝试过将“ Persistence Enabled”设置为false，但仍然没有运气:(。

// a view model for a data entity called topics
// the topicsHashMap is a Mutable Live data and being observed actively in the activity
//the hashmap is structured as follows: a community has multiple topics so hashmap has community id as key and arraylist of topics as items under the key in the hashmap
mTopicsViewModel.getTopicsHashMap().observe(mActivity, new Observer<HashMap<String, ArrayList<Topic>>>() {
    @Override
    public void onChanged(HashMap<String, ArrayList<Topic>> topicsHashMap) {
        //getting the topics here
        ArrayList<Topic> topics = topicsHashMap.get(mCommunityID);
        //getting the current topics from the array list
        Topic newTopic = topicsHashMap.get(mCommunityID).get(topics.indexOf(new Topic(mTopicID,null,null,null,0)));
        //voting is an attribute of the topic object, I need to observe the voting changes in my activity. These changes are being returned twice.
        //checking if current voting is not same as the new voting then change all ui
        if(mCurrentVoting!=newTopic.voting){
            mCurrentTopic = newTopic;
            mCurrentVoting = mCurrentTopic.voting;
            //voting alert dialog reflects all these changes in voting in real time
            if(votingAlertDialog!=null){
                if(votingAlertDialog.isShowing()) {
                    //then you need to update the views inside voting alert dialog as well
                    if (!userOption.name.isEmpty()) {
                        Logger.d("New voting added "+mCurrentVoting);
                        // calling the function that changes the ui accordingly
                        showVotingChangesOnAlertDialog();
                    }
                }
            }
        }else{
            Logger.d("Ignoring this voting change because its similar to previous");
        }


    }
});

对于每个数据库更改，仅预期对onDataChanged的一次调用； 但是，收到两个。