Наценка за доставку и вывод

Подскажите как в методе onItemSelected() при выборе элемента из spinner при совпадении например значения "Самовывоз" прибавить сумму за доставку, допустим 350 и вывести эту наценку в методе getDataFromDatabase()

public class ActivityCheckout extends AppCompatActivity {

private void getSpinnerData() {

    arrayList = new ArrayList<String>();
    spinner = findViewById(R.id.spinner);

    StringRequest stringRequest = new StringRequest(GET_SHIPPING, new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    JSONObject jsonObject = null;
                    try {
                        jsonObject = new JSONObject(response);
                        result = jsonObject.getJSONArray("result");
                        getShipping(result);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }

                    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                        @Override
                        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                            edt_shipping.setText(setShipping(i));
                            if (spinner.getSelectedItem().toString().trim().equals("Самовывоз")) {
                               // здесь вместо Toast при выборе элемента Самовывоз делаем наценку Toast.makeText(ActivityCheckout.this, " выбран самовывоз", Toast.LENGTH_SHORT).show(); }
                        }

                        @Override
                        public void onNothingSelected(AdapterView<?> adapterView) {

                        }
                    });

                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);

}

private void getShipping(JSONArray jsonArray) {
    for (int i = 0; i < jsonArray.length(); i++) {
        try {
            JSONObject json = jsonArray.getJSONObject(i);
            arrayList.add(json.getString("shipping_name"));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    ArrayAdapter<String> myAdapter = new ArrayAdapter<String>(ActivityCheckout.this, R.layout.spinner_item, arrayList);
    myAdapter.setDropDownViewResource(R.layout.spinner_dropdown_item);
    spinner.setAdapter(myAdapter);
}

private String setShipping(int position) {
    String name = "";
    try {
        JSONObject json = result.getJSONObject(position);
        name = json.getString("shipping_name");
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return name;
}

public void submitOrder() {
    btn_submit_order.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            getValueFromEditText();
        }
    });
}

public void getDataFromDatabase() {

    data = dbhelper.getAllData();

    double Order_price = 0;
    double Total_price = 0;
    double tax = 0;

    for (int i = 0; i < data.size(); i++) {
        ArrayList<Object> row = data.get(i);

        String Menu_name = row.get(1).toString();
        String Quantity = row.get(2).toString();

        double Sub_total_price = Double.parseDouble(row.get(3).toString());

        String _Sub_total_price = String.format(Locale.GERMAN, "%1$,.0f", Sub_total_price);

        Order_price += Sub_total_price;

        if (Config.ENABLE_DECIMAL_ROUNDING) {
            data_order_list += (Quantity + " " + Menu_name + " " + _Sub_total_price + " " + str_currency_code + ",\n");
        } else {
            data_order_list += (Quantity + " " + Menu_name + " " + Sub_total_price + " " + str_currency_code + ",\n");
        }
    }

    if (data_order_list.equalsIgnoreCase("")) {
        data_order_list += getString(R.string.no_order_menu);
    }

    tax = 0;
    Total_price = Order_price + tax;


    String price_tax = String.format(Locale.GERMAN, "%1$,.0f", str_tax);
    String _Order_price = String.format(Locale.GERMAN, "%1$,.0f", Order_price);
    String _tax = String.format(Locale.GERMAN, "%1$,.0f", tax);
    String _Total_price = String.format(Locale.GERMAN, "%1$,.0f", Total_price);

    if (Config.ENABLE_DECIMAL_ROUNDING) {
        data_order_list += "\n" + getResources().getString(R.string.txt_order) + " " + _Order_price + " " + str_currency_code + " доставка вышла:";


        edt_order_total.setText(_Total_price + " " + str_currency_code);

    } else {
        //здесь нужно вывести эту наценку  data_order_list += "\n" + getResources().getString(R.string.txt_order) + " " + Order_price + " " + str_currency_code + " доставка вышла:" + наценка;

        edt_order_total.setText(Total_price + " " + str_currency_code);
    }

    edt_order_list.setText(data_order_list);

}

public void dialogSuccessOrder() {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle(R.string.checkout_success_title);
    builder.setIcon(R.drawable.received);
    builder.setMessage(R.string.checkout_success_msg);
    builder.setCancelable(false);
    builder.setPositiveButton(R.string.checkout_option_ok, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            dbhelper.addDataHistory(rand, str_order_list, str_order_total, date);
            dbhelper.deleteAllData();

            Intent intent = new Intent(getApplicationContext(), MainActivity.class);
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
            startActivity(intent);
        }
    });
    AlertDialog alert = builder.create();
    alert.show();
}

}