simpleCalendarView.setOnDateChangeListener(new CalendarView.OnDateChangeListener() {
        @Override
        public void onSelectedDayChange(CalendarView view, int year, int month, int dayOfMonth) {
            // display the selected date by using a toast
            int y = year;
            int m = month + 1;
            int d = dayOfMonth;
            final String date = d + "/" + m + "/" + y;
            final ProgressDialog loading = ProgressDialog.show(Daily_Attendance.this, "Processing...", "Please wait...", false, false);

            StringRequest stringRequest = new StringRequest(Request.Method.POST, url3, new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    try {
                        Log.d("rr",response);
                        loading.dismiss();
                        JSONArray j = new JSONArray(response);
                        JSONObject jo = j.getJSONObject(0);
                        String res = jo.getString("result");
                        if (res.equals("true")) {
                            alert.setMessage("You Were Present on " + date)
                                    .setPositiveButton("ok", new DialogInterface.OnClickListener() {
                                        @Override
                                        public void onClick(DialogInterface dialog, int which) {
                                            dialog.dismiss();
                                        }
                                    })
                                    .show();
                        }
                        if (res.equals("false")) {

                            alert.setMessage("You were Absent on " + date)
                                    .setPositiveButton("ok", new DialogInterface.OnClickListener() {
                                        @Override
                                        public void onClick(DialogInterface dialog, int which) {
                                            dialog.dismiss();
                                        }
                                    })
                                    .show();
                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }

                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    loading.dismiss();
                    Toast.makeText(Daily_Attendance.this, "Connection Error..", Toast.LENGTH_SHORT).show();
                }
            }) {
                @Override
                protected Map<String, String> getParams() throws AuthFailureError {
                    Map<String, String> param = new HashMap<>();
                    param.put("date", date);
                    param.put("semester", semester);
                    param.put("section", section);
                    param.put("subject_name", subject_name);
                    param.put("subject_type", subject_type);
                    param.put("subject_code", subject_code);
                    param.put("registration_number",user.get(sessionManagement.KEY_REGISTRATION_NUMBER));
                    return param;
                }
            };
            AppController.getInstance().addToRequestQueue(stringRequest);

        }
    });