Firebase.database（）。ref（“ RefNode”）。set（null）触发该引用的OnDataChanged

Question

I have nodejs server and an android client . Both are connected to my firebase database . When the server sets the "RefNode" to null , the onDataChanged Callback, that is set on that "RefNode" on the andriod side, gets called.

Is there any way to avoid it being called in the special case when the "RefNode" was set to null while for all other cases it should get called.

I have a listener on a node "RefNode" in my android application as given below: The OnDataChanged() callback is getting called even when the "RefNode" was set to null by the nodejs server.

FirbaseDatabase.getInstance().getReference().child("RefNode").addValueEventListener( new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if(dataSnapshot.exists()){
                if(dataSnapshot.getValue()!=null) {
                    Log.v(TAG, "got here even when the Refnode was set to null");
                }
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            // The listener got cancelled
        }
});

Answer 1

I have found the problem I had attached the event listener twice. I had made the ValueEventListener a field of the class the and attached it twice.