private void calculateYearExpense(Fragment fragment, int selectedYear) {
        final List<Double> expenses = new ArrayList<>();

        db.collection("Year").whereEqualTo("year", selectedYear)
                .get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                final String yearDocumentId = Objects.requireNonNull(task.getResult()).getDocuments().get(0).getId();

                db.collection("Year/" + yearDocumentId + "/Month").get()
                        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                            @Override
                            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                                for (int i = 0; i < Objects.requireNonNull(task.getResult()).getDocuments().size(); i++) {
                                    String monthDocumentId = task.getResult().getDocuments().get(i).getId();

                                    db.collection("Year/" + yearDocumentId + "/Month/" + monthDocumentId + "/Bill")
                                            .get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                                        @Override
                                        public void onComplete(@NonNull Task<QuerySnapshot> task) {
                                            for (int i = 0; i < Objects.requireNonNull(task.getResult()).getDocuments().size(); i++) {
                                                expenses.add(task.getResult().getDocuments().get(i).getDouble("billExpense"));
                                            }

double result = 0.0;

        for (int i = 0; i < expenses.size(); i++) {
            result += expenses.get(i);
        }

Bundle bundle = new Bundle();
                    bundle.putString("yearExpenseDescription", yearExpenseDescription);
                    fragment.setArguments(bundle);
                                        }
                                    });
                                }
                            }
                        });
            }
        });
    }

}