Random Firebase query [Android]

I need to use Collections.shuffle() at the recyclerView , But it is not possible because I use firebase query :

 query=FirebaseDatabase.getInstance().getReference("Videos").orderByChild("s").equalTo("1");

so Collections.shuffle((List<?>) query2); will show an error

Also I tried to user startAt() in side query but I could't detect the key and value of child s in the same query.

so please help me