Usually to avoid Exceptions brought about by the code running in UI thread, run the request and response process in a worker thread (Thread or Asynch task) depending on the anticipated length of the process.
    private void runInBackround(){
       new Thread(new Runnable() {
            @Override
            public void run() { 
                //method containing process logic.
                makeNetworkRequest(reqUrl);
            }
        }).start();
    }
    private void makeNetworkRequest(String reqUrl) {
       Log.d(TAG, "Booking started: ");
       OkHttpClient httpClient = new OkHttpClient();
       String responseString = "";
       Calendar c = Calendar.getInstance();
       SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
       String booked_at = sdf.format(c.getTime());
         try{
             RequestBody body = new FormBody.Builder()
                .add("place_id", id)
                .add("booked_at", booked_at)
                .add("booked_by", user_name.getText().toString())
                .add("booked_from", lat+"::"+lng)
                .add("phone_number", user_phone.getText().toString())
                .build();
        Request request = new Request.Builder()
                .url(reqUrl)
                .post(body)
                .build();
        Response response = httpClient
                .newCall(request)
                .execute();
        responseString =  response.body().string();
        response.body().close();
        Log.d(TAG, "Booking done: " + responseString);
        // Response node is JSON Object
        JSONObject booked = new JSONObject(responseString);
        final String okNo = booked.getJSONArray("added").getJSONObject(0).getString("response");
        Log.d(TAG, "Booking made response: " + okNo);
        runOnUiThread(new Runnable()
        {
            public void run()
            {
                if("OK" == okNo){
                    //display in short period of time
                    Toast.makeText(getApplicationContext(), "Booking Successful", Toast.LENGTH_LONG).show();
                }else{
                    //display in short period of time
                    Toast.makeText(getApplicationContext(), "Booking Not Successful", Toast.LENGTH_LONG).show();
                }
            }
        });
    } catch (MalformedURLException e) {
        Log.e(TAG, "MalformedURLException: " + e.getMessage());
    } catch (ProtocolException e) {
        Log.e(TAG, "ProtocolException: " + e.getMessage());
    } catch (IOException e) {
        Log.e(TAG, "IOException: " + e.getMessage());
    } catch (Exception e) {
        Log.e(TAG, "Exception: " + e.getMessage());
    }
}
I hope it helps someone there.