Android ArrayList<String> stored not restored back to its saved sorted order

Question

1. I have an myArrayList which is to be stored and restored back in its saved sorted order. But the code does not do that. Why?

   ArrayList<String> myArrayList
   
   // save:
           SharedPreferences prefs = PreferenceManager
           .getDefaultSharedPreferences(getBaseContext());
   SharedPreferences.Editor edit;
   edit = prefs.edit();
   edit.putStringSet("mydata", new LinkedHashSet<String>(myArrayList));
   edit.commit();
   
       // read:
   myArrayList = new ArrayList<String>(PreferenceManager
           .getDefaultSharedPreferences(getBaseContext()).getStringSet(
                   "mydata", new LinkedHashSet<String>()));
   adapterAppList = new ArrayAdapter<String>(this,
           android.R.layout.simple_list_item_1, android.R.id.text1,
           myArrayList);
   

2. Is there any better way I can store the value of myArrayList and restored back to its original saved sorted order?

Answer 1

You can serialize arrayList like string:

1 with gson

public ArrayList<String> convertToArrayList(String json) {
    if (TextUtils.isEmpty(json)){
        return null; // or new ArrayList<>()
    }
    Type type = new TypeToken<ArrayList<String>>(){}.getType();
    return new Gson().fromJson(json, type);
}
public String convertFromArrayList(ArrayList<String> list) {
    if (list == null){
        return null;
    }
    return new Gson().toJson(list);
}

2 without gson

public ArrayList<String> convertToArrayList(String st) {
    if (!TextUtils.isEmpty(st)){
        String[] str = st.split(",");
        if (str.length > 0){
            return new ArrayList<>(Arrays.asList(str));
        }
    }
    return null;
}
public String convertFromArrayList(ArrayList<String> list) {
    if (list!=null && !list.isEmpty()){
        return TextUtils.join(",", list);
    }
    return null;
}