progress bar not update when read firebase records

Question

I use next code to save firebase records to my array list:

List<PoIs> LocoList = new ArrayList<>();
DatabaseReference ref = 
FirebaseDatabase.getInstance().getReference("DATABASE");

ProgressBar progressBar = dialog.findViewById(R.id.progressBar);
progressBar.setProgress(0);


    ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        if (dataSnapshot.exists()) {

            int size = (int) dataSnapshot.getChildrenCount();
            progressBar.setMax(size);
           
            for (DataSnapshot ds : dataSnapshot.getChildren()) {
                PoIs loco = ds.getValue(PoIs.class);
                LocoList.add(loco);

                progressBar.setProgress(LocoList.size());

..........

The problem is that my progressbar is updated just at final. Progress bar stay at zero to ten seconds then jump directly to 3000.

Any suggestion how to redraw my progress bar for every setProgress?