Is there any benefit to using gson/json for shared preferences instead of doing it manually

Question

I have to save into shared preferences the users alarms which is an object comprising of booleans and ints. There will obviously be multiple alarms saved one after the other. My initial action was to use string builder and save the alarms as one long string seperated by commas and semicolons.

I did that like this:

// Encode the preferences into a single string with "," ready to be unencoded when opening the list again.
  StringBuilder alarmString = new StringBuilder();

  alarmString.append(alarmHour+","+alarmMinute+","+mondaySelected+","+tuesdaySelected+","+wednesdaySelected+","+
  thursdaySelected+","+fridaySelected+","+saturdaySelected+","+sundaySelected);

  // Access the shared preferences to see if the user has saved any alarms yet
  SharedPreferences sharedPreferences = getActivity().getSharedPreferences("AppData", Context.MODE_PRIVATE);
  String alarms = sharedPreferences.getString("AlarmsString", "None");

  if (alarms == "None"){

      // Save the users alarm preferences to the alarms string encoded string
      SharedPreferences.Editor editor = sharedPreferences.edit();
      editor.putString("AlarmsString", alarmString.toString());
      editor.apply();
      Toast.makeText(getActivity(), alarmString, Toast.LENGTH_SHORT).show();

  } else {

      String alarmStringAppended = alarms + alarmString;

      SharedPreferences.Editor editor = sharedPreferences.edit();
      editor.putString("AlarmsString", alarmStringAppended);
      editor.apply();

      Toast.makeText(getActivity(), alarmStringAppended, Toast.LENGTH_SHORT).show();

      }

I would then break the string back up on the other side.

But then I read it is better to save it as json/gson serialised like this (Incomplete code):

  Alarm alarmObject=new Alarm(alarmHour, alarmMinute, mondaySelected, tuesdaySelected,
          wednesdaySelected, thursdaySelected, fridaySelected, saturdaySelected, sundaySelected);

  SharedPreferences appSharedPrefsave = PreferenceManager
          .getDefaultSharedPreferences(getActivity());
  SharedPreferences.Editor prefsEditor = appSharedPrefsave.edit();
  Gson gsonsave = new Gson();
  String jsonsave = gsonsave.toJson(alarmObject);
  prefsEditor.putString("MyAlarms", jsonsave);
  prefsEditor.commit();


  SharedPreferences appSharedPrefsRetrieve = PreferenceManager
          .getDefaultSharedPreferences(getActivity());
  Gson gson = new Gson();
  String json = appSharedPrefsRetrieve.getString("MyObject", "");
  Alarm mStudentObject = gson.fromJson(json, Alarm.class);

Is there a preferred way and are there any memory issues having to loop through the strings ect or is my original way of doing it just as valid (although long winded).

Haven't checked it haha. Was about to then. Was just going to set a default value if there was nothing. It would explain another bug I am having in another program if that is not correct haha. — Nicholas Muir, Sep 20 '16 at 01:21
Was more wondering as an overview not really a comment on my code is there problems with doing it manually versus gson/json — Nicholas Muir, Sep 20 '16 at 01:22
Anyways, concatenating strings does have over head compared to a StringBuilder, but probably less than serializing an object to JSON. I think this really depends on the broader use of Gson in your application — OneCricketeer, Sep 20 '16 at 01:22
Regarding first comment - http://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java — OneCricketeer, Sep 20 '16 at 01:24
If this is the only use, then I'd suggest making the Alarm object implement Parcelable. I think SharedPreferences can store those — OneCricketeer, Sep 20 '16 at 01:25

score 1 · Answer 1 · answered Apr 04 '17 at 16:22

You certainly can write your own serializer/deserializer, but why would you? Turn the question around - what's the benefit of you reinventing the wheel?

Not only is serialization code tedious and often tricky to get right, but it's a heavily studied problem, and there are countless libraries that exist to make your life easier. If JSON/Gson seems too heavyweight for your use case you might consider alternatives like Properties, YAML, CSV, or even SQL, but writing your own is just time you could spend doing real work.

Is there any benefit to using gson/json for shared preferences instead of doing it manually

1 Answers1