Android Firebase Realtime Database orderByChild is not working

Question

I'm trying to sort the restaurants by the average rating with orderByChild() but instead of returning them by sorting them by average rating it doesn't.

Here is my code:

public void filterQuality(){

    DatabaseReference mRatingDb = FirebaseDatabase.getInstance().getReference();

    Query topQualityQuery = mRatingDb.orderByChild("Average");
    topQualityQuery.addListenerForSingleValueEvent(new ValueEventListener() 
    {

        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            Map <String, Double> topQualityMap = new HashMap<>();
            List list = new ArrayList();
            List list2 = new ArrayList();  

            for (DataSnapshot ds: dataSnapshot.getChildren()){

                topQualityMap.put(ds.getKey(), ds.child("Quality").child("Average").getValue(double.class));
                list.add(ds.child("Quality").child("Average").getValue(double.class));
                list2.add(ds.getKey());

                Log.d("Top Quality", "Value" + topQualityMap);
                Log.d("Top Quality", "Value" + list);
                Log.d("Top Quality", "Value" + list2);
            }

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

}

This is what I get from maps and lists from what I tried to debug:

Value [3.0]

Value [Jurys Inn Newcastle]

Value {Malmaison Newcastle=2.0, Jurys Inn Newcastle=3.0}

D/Top Quality: Value [3.0, 2.0]

D/Top Quality: Value [Jurys Inn Newcastle, Malmaison Newcastle]

D/Top Quality: Value {Malmaison Newcastle=2.0, Jurys Inn Newcastle=3.0, The County Hotel, Newcastle=4.0}

Value [3.0, 2.0, 4.0]

Value [Jurys Inn Newcastle, Malmaison Newcastle, The County Hotel, Newcastle]

Here is my firebase:

If someone knows why this is not working properly please help. Thank you.

Answer 1

You'll need to specify the full path to the value you want to order on.

So:

DatabaseReference mRatingDb = FirebaseDatabase.getInstance().getReference();

Query topQualityQuery = mRatingDb.orderByChild("Quality/Average");
topQualityQuery.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
        for (DataSnapshot ds: dataSnapshot.getChildren()){
            Log.i("Firebase", ds.getKey()+": "+ ds.child("Quality/Average").getValue(double.class));
        }
    }
    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        throw databaseError.toException(); // NEVER ignore errors
    } 
});