private void LoadUserPreference()
        {
            string userPreferenceSerialize = string.Empty;

            if (String.IsNullOrEmpty(Properties.Settings.Default.FileExtension) == true)
            {
                Models.ValidExtensionData valid = new Models.ValidExtensionData();
                userPreferenceSerialize = JsonConvert.SerializeObject(valid);
                Properties.Settings.Default.FileExtension = userPreferenceSerialize;
                Properties.Settings.Default.Save();
            }
            else
            {
                userPreferenceSerialize = Properties.Settings.Default.FileExtension;
            }


            int indexStart         = userPreferenceSerialize.IndexOf('[');
            int indexEnd           = userPreferenceSerialize.LastIndexOf(']');
            int countCharEndString = userPreferenceSerialize.Length - indexEnd;

            string clean = userPreferenceSerialize.Substring(indexStart, userPreferenceSerialize.Length - (indexStart + countCharEndString) + 1);

            List <Models.ExtensionData> deserializedName = JsonConvert.DeserializeObject <List <Models.ExtensionData> >(clean);

            foreach (Models.ExtensionData item in deserializedName)
            {
                UserPreferenceList.Add(item);
            }
        }
        private void SavePreferenceExecute(object obj)
        {
            Models.ValidExtensionData validExtensionData = new Models.ValidExtensionData(UserPreferenceList);
            string userPreferenceSerialize = JsonConvert.SerializeObject(validExtensionData);

            Properties.Settings.Default.FileExtension = userPreferenceSerialize;
            Properties.Settings.Default.Save();

            // Configure the message box to be displayed
            string           messageBoxText = "User Preference Saved";
            string           caption        = "File Extension";
            MessageBoxButton button         = MessageBoxButton.OK;
            MessageBoxImage  icon           = MessageBoxImage.Information;

            // Display message box
            MessageBox.Show(messageBoxText, caption, button, icon);
        }