Tukukkk

This is my firebase database structure.

I want to fetch the values of "Total" of all children of "Bill". I have tried to fetch the data but my code is not working. Here is my code.

 DatabaseReference billReference = FirebaseDatabase.getInstance().getReference().child("Bill");

        billReference.addValueEventListener(new ValueEventListener() {

            @Override

            public void onDataChange(DataSnapshot dataSnapshot) {

                int i = 0;

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

                    fetchCount++;

                    Toast.makeText(getApplicationContext(),""+keys[i],Toast.LENGTH_LONG).show();

                    String temp = ds.child(keys[i]).child("Breakfast").child("11-2018").child("Total").getValue().toString();

                    breakfastBills.add(names[i] + " : " + temp);

                    i++;

                }

                if (fetchCount == 4) {

                    AlertDialog.Builder builder = new AlertDialog.Builder(bill_details_manager.this);

                    builder.setTitle("Bill Details for Breakfast");

                    builder.setItems(breakfastBills.toArray(new String[breakfastBills.size()]), new DialogInterface.OnClickListener() {

                        @Override

                        public void onClick(DialogInterface dialogInterface, int i) {



                        }

                    });

                    progressDialog.dismiss();

                    AlertDialog alertDialog = builder.create();

                    alertDialog.show();



                }

What is wrong with this code ?

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

    billRef.child("Bill").addListenerForSingleValueEvent(new ValueEventListener() {

        @Override

        public void onDataChange(@NonNull DataSnapshot allValueSnap) {

            for (DataSnapshot snapshot: allValueSnap.getChildren()){

                String key = snapshot.getKey();

                if (key != null) {

                    billRef.child("Bill").child(key).child("Breakfast").addListenerForSingleValueEvent(new ValueEventListener() {

                        @Override

                        public void onDataChange(@NonNull DataSnapshot keySnapshot) {

                            for (DataSnapshot dateSnapshot:keySnapshot.getChildren()){

                                String keyDate = dateSnapshot.getKey();

                                long totalValue =(long) keySnapshot.child(keyDate).child("Total").getValue();

                                Log.i("totalBreakFast","STotal: "+String.valueOf(totalValue));

                                breakfastBills.add(totalValue);

                            }

                            if(!keySnapshot.exists()){

                                Log.i("totalBreakFast","NoData: ");

                            }

                        }

                        @Override

                        public void onCancelled(@NonNull DatabaseError databaseError) {



                        }

                    });

                }



            }

        }

        @Override

        public void onCancelled(@NonNull DatabaseError databaseError) {



        }

    });

This code is getting all values of "Total".