Example of POST method to call webservice with Volley

PriceConfirmationTask.java

public class PriceConfirmationTask {
    private Callback mCallback;
    String mDeliveryTime;
    Activity mActivity;

    public interface Callback{
        public void onResponse(PriceCheckResult result);
    }
    public PriceConfirmationTask(Activity activity, String deliveryTime, Callback callback) {
        mActivity = activity;
        mDeliveryTime = deliveryTime;
        mCallback = callback;
    }
    public PriceCheckResult parseXML(String input){
        {
            try {
                XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
                factory.setNamespaceAware(true);
                XmlPullParser xpp = null;

                xpp = factory.newPullParser();
                xpp.setInput(new StringReader(input));
                int eventType = 0;
                eventType = xpp.getEventType();
                String currentTag="";
                Log.d("ddw","input: "+input);
                int foodMainItemPosition = 0;
                int extraItemPosition = 0;
                int miscChargesPosition = 0;
                PriceCheckResult priceCheckResult = new PriceCheckResult();
                while (eventType != XmlPullParser.END_DOCUMENT) {
                    if(eventType == XmlPullParser.START_DOCUMENT) {
                        System.out.println("Start document");
                    } else if(eventType == XmlPullParser.END_DOCUMENT) {
                        System.out.println("End document");
                    } else if(eventType == XmlPullParser.START_TAG) {
                        currentTag = xpp.getName();
                        System.out.println("Start tag "+xpp.getName());
                    } else if(eventType == XmlPullParser.END_TAG) {
                        currentTag = xpp.getName();
                        System.out.println("End tag "+xpp.getName());
                        if (currentTag.equals("FoodMainItem")){
                            foodMainItemPosition++;
                            extraItemPosition = 0;
                        } else if (currentTag.equals("MiscChargess")){
                            miscChargesPosition++;
                        }
                    } else if(eventType == XmlPullParser.TEXT) {
                        System.out.println("tag, Text "+currentTag+","+xpp.getText());
                        if (currentTag.equals("CustomerID")){
                            priceCheckResult.CustomerID = xpp.getText();
                        } else if (currentTag.equals("Email")){
                            priceCheckResult.Email = xpp.getText();
                        } else if (currentTag.equals("Contact")){
                            priceCheckResult.Contact = xpp.getText();
                        } else if (currentTag.equals("RestaurantID")){
                            priceCheckResult.RestaurantID = xpp.getText();
                        } else if (currentTag.equals("TimePickup")){
                            priceCheckResult.TimePickup = xpp.getText();
                        } else if (currentTag.equals("VoucherCode")){
                            priceCheckResult.VoucherCode = xpp.getText();
                        } else if (currentTag.equals("product_id")){
                            if (priceCheckResult.foodItems.size() == foodMainItemPosition){
                                priceCheckResult.foodItems.add(new FoodMainItem());
                            }
                            priceCheckResult.foodItems.get(foodMainItemPosition).product_id = xpp.getText();
                        } else if (currentTag.equals("qty")){
                            if (priceCheckResult.foodItems.size() == foodMainItemPosition){
                                priceCheckResult.foodItems.add(new FoodMainItem());
                            }
                            priceCheckResult.foodItems.get(foodMainItemPosition).qty = xpp.getText();
                        } else if (currentTag.equals("name")){
                            if (priceCheckResult.foodItems.size() == foodMainItemPosition){
                                priceCheckResult.foodItems.add(new FoodMainItem());
                            }
                            priceCheckResult.foodItems.get(foodMainItemPosition).name = xpp.getText();
                        } else if (currentTag.equals("unit_price")){
                            if (priceCheckResult.foodItems.size() == foodMainItemPosition){
                                priceCheckResult.foodItems.add(new FoodMainItem());
                            }
                            priceCheckResult.foodItems.get(foodMainItemPosition).unit_price = xpp.getText();
                        } else if (currentTag.equals("price")){
                            if (priceCheckResult.foodItems.size() == foodMainItemPosition){
                                priceCheckResult.foodItems.add(new FoodMainItem());
                            }
                            priceCheckResult.foodItems.get(foodMainItemPosition).price = xpp.getText();
                        } else if (currentTag.equals("ChargeDesc")){
                            if (priceCheckResult.MiscChargess.size() == miscChargesPosition){
                                priceCheckResult.MiscChargess.add(new MiscCharge());
                            }
                            priceCheckResult.MiscChargess.get(miscChargesPosition).ChargeDesc = xpp.getText();
                        } else if (currentTag.equals("ChargeAmount")){
                            if (priceCheckResult.MiscChargess.size() == miscChargesPosition){
                                priceCheckResult.MiscChargess.add(new MiscCharge());
                            }
                            priceCheckResult.MiscChargess.get(miscChargesPosition).ChargeAmount = xpp.getText();
                        } else if (currentTag.equals("TotalCharges")){
                            priceCheckResult.TotalCharges = xpp.getText();
                        }
                    }
                    eventType = xpp.next();
                }
                Log.d("ddw","priceCheckResult: "+priceCheckResult);
                return priceCheckResult;
            } catch (XmlPullParserException e) {
                e.printStackTrace();
                return null;
            } catch (IOException e) {
                e.printStackTrace();
                return null;
            }
        }
    }
    public void callEndpoint() {

        try {
            final StringRequest stringRequest = new StringRequest(Request.Method.POST, ApiConstant.KSOAP_BASE_URL, new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    Log.d("ddw", "PopulateCart response: " + response.toString());
                    Log.d("ddw", "parseXML(response): " + response.toString());
                    mCallback.onResponse(parseXML(response));
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.d("ddw", "Error: " + error.getMessage());
                    Log.d("ddw", ""+error.getMessage()+","+error.toString());
                }
            }){
                @Override
                public Map<String, String> getParams(){
                    return null;
                }
                @Override
                public byte[] getBody(){
                    List<Menu> foods = Menu.listAll(Menu.class);

                    String foodItemString = "";
                    // Make food requests
                    for(Menu food:foods){
                        foodItemString+="        <ns1:FoodItems>\n" +
                                "          <ns1:FoodMainItem>\n" +
                                "            <ns1:product_id>"+food.getProduct_id()+"</ns1:product_id>\n" +
                                "            <ns1:qty>"+food.getQuantity()+"</ns1:qty>\n" +
                                "          </ns1:FoodMainItem>\n" +
                                "        </ns1:FoodItems>\n";
                    }
//                        Log.d("ddw","foodItemString: "+foodItemString);

                    String temp = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                            "<SOAP-ENV:Envelope xmlns:SOAP-ENV=\"http://schemas.xmlsoap.org/soap/envelope/\" xmlns:ns1=\"http://tempuri.org/\">\n" +
                            "  <SOAP-ENV:Body>\n" +
                            "    <ns1:PopulateCart>\n" +
                            "      <ns1:sc>\n" +
                            "        <ns1:CustomerID>"+ Common.getSharedPrefValue(mActivity, Common.PREF_TOKEN_ID)+"</ns1:CustomerID>\n" +
                            "        <ns1:Email>"+ Common.getSharedPrefValue(mActivity, Common.PREF_EMAIL)+"</ns1:Email>\n" +
                            "        <ns1:Contact></ns1:Contact>\n" +
                            "        <ns1:RestaurantID>"+ Restaurant.listAll(Restaurant.class).get(0).getRestaurant_id()+"</ns1:RestaurantID>\n" +
                            "        <ns1:TimePickup>"+mDeliveryTime+"</ns1:TimePickup>\n" +
                            "        <ns1:VoucherCode></ns1:VoucherCode>\n" +
                            foodItemString+
                            "      </ns1:sc>\n" +
                            "    </ns1:PopulateCart>\n" +
                            "  </SOAP-ENV:Body>\n" +
                            "</SOAP-ENV:Envelope>\n";
//                        byte[] b = temp.getBytes();
                    Log.d("ddw","request String: "+temp);
                    byte[] b = temp.getBytes(Charset.forName("UTF-8"));

                    return b;
                }
                @Override
                public String getBodyContentType()
                {
                    return "text/xml;charset=utf-8";
                }
            };
            new Thread(new Runnable() {
                public void run() {
                    RequestQueue queue = Volley.newRequestQueue(mActivity);
                    queue.add(stringRequest);
                }
            }).start();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

hi
this code is not working for me
responce is 500 so how to parse