Top5 on Firebase Android

 private void setMoreViewed(String itemViewed, String user) {
        refViewed = data.getReference("/cliente/" + user + "/top5");
        Map<Integer, String> top5_map = new HashMap<>();
        refViewed.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot ds) {

                for (DataSnapshot tmp : ds.getChildren()) {
                    top5_map.put(Integer.parseInt(tmp.getKey()), tmp.getValue(String.class));
                }
                switch (top5_map.size()) {
                    case 0:
                        top5_map.put(1, itemViewed);
                        break;
                    case 1:
                        if (!top5_map.containsValue(itemViewed)) {
                            top5_map.put(2, top5_map.get(1));
                            top5_map.replace(1, itemViewed);
                        }
                        break;
                    case 2:
                        if (!top5_map.containsValue(itemViewed)) {
                            top5_map.put(3, top5_map.get(2));
                            top5_map.replace(2, top5_map.get(1));
                            top5_map.replace(1, itemViewed);
                        }
                        break;
                    case 3:
                        if (!top5_map.containsValue(itemViewed)) {
                            top5_map.put(4, top5_map.get(3));
                            top5_map.replace(3, top5_map.get(2));
                            top5_map.replace(2, top5_map.get(1));
                            top5_map.replace(1, itemViewed);
                        } else {
                            top5_map.replace(1, itemViewed);
                        }
                        break;
                    case 4:
                        if (!top5_map.containsValue(itemViewed)) {
                            top5_map.put(5, top5_map.get(4));
                            top5_map.replace(4, top5_map.get(3));
                            top5_map.replace(3, top5_map.get(2));
                            top5_map.replace(2, top5_map.get(1));
                            top5_map.replace(1, itemViewed);
                        } else {
                            top5_map.replace(1, itemViewed);
                        }

                        break;
                    case 5:
                        if (!top5_map.containsValue(itemViewed)) {
                            top5_map.replace(5, top5_map.get(4));
                            top5_map.replace(4, top5_map.get(3));
                            top5_map.replace(3, top5_map.get(2));
                            top5_map.replace(2, top5_map.get(1));
                            top5_map.replace(1, itemViewed);
                        } else {
                            top5_map.replace(1, itemViewed);
                        }
                        break;
                }
                for (Map.Entry<Integer, String> entry : top5_map.entrySet()) {
                    refViewed.child(String.valueOf(entry.getKey())).setValue(entry.getValue());
                }
            }
            @Override
            public void onCancelled(DatabaseError de) {

            }
        });

    }