private static void verifyPayment(Payment payment) { string resultString = "".ToString(); JSONObject jsonObject = new JSONObject(); jsonObject.Put("payload", payment.Payload); string verifystring = (string)jsonObject; //Map<string, string> headers = new HashMap<>(); //headers.Put("Content-Type", "application/json; charset=UTF-8"); //headers.Put(merchantApiHeaderKeyForApiSecretKey, merchantApiSecretKey); Dictionary <string, string> headers = new Dictionary <string, string>(); headers.Add("Content-Type", "application/json; charset=UTF-8"); headers.Add(merchantApiHeaderKeyForApiSecretKey, merchantApiSecretKey); // AsyncHttpClient.Post(merchantServerUrl + VERIFY, headers, verifystring, new HttpResponseCallback { Success = (response) => { Java.Lang.String mString = new Java.Lang.String(response, Charset.ForName("UTF-8")); JSONObject jsonVerifyResponse = new JSONObject((string)mString); Java.Lang.String authResponse = new Java.Lang.String(jsonVerifyResponse.GetString("authResponse")); if (authResponse.EqualsIgnoreCase(payment.GetPaymentStatus().ToString())) { resultString = "Payment is " + payment.GetPaymentStatus().ToString().ToLower() + " and verified."; } else { resultString = "Failed to verify payment."; } }, Failure = (th) => { Toast.MakeText(context, resultString, ToastLength.Long).Show(); } }); }