How to save Calendar data in shared preferences : Android

Question

I have a ArrayList of Calendar type, And I need to save its data into SharedPreferences. I can save String ArrayList data by using this code:

Set<String> setName = new HashSet<String>();
setName.addAll(ignoredProcesses);
SharedPreferences shrdPref = getSharedPreferences("sharePref", MODE_PRIVATE);
SharedPreferences.Editor prefEditor = shardPref.edit();
prefEditor.putStringSet("keyValue", setName);
prefEditor.commit();

But if I'm following the same approach to save Calendar data, I'm getting error to change Set type to String.

How can I save ArrayList <Calendar> list = new ArrayList<Calendar>(); into SharedPreferences and how I to get it back from SharedPrefernces. Your help will be very appreciated. Thank you

Answer 1

You will have to convert each of your calendar to long using method Calendar.getTimeInMillis() and then save it in your preference using method putLong(key, long). You will have to change the key for each entry. Here is an example:

    SharedPreferences shrdPref = getSharedPreferences("sharePref",MODE_PRIVATE);
    SharedPreferences.Editor prefEditor = shardPref.edit();
       for(int i = 0; i<list.size();i++){
          long millis = list.get(i).getTimeInMillis();
          prefEditor.putLong("calendar"+i,millis);
          prefEditor.commit();
       }

You would then retrieve them with:

int i =0;
while(shrdPref.getLong("calendar"+i,0)!=0){
   Calendar cal = new GregorianCalendar();
   cal.setTimeInMillis(shrdPref.getLong("calendar"+i,0));
   list.add(cal);
   i++;
}

Bit of a hack, not sure if it works, try it and let me know.