SharedPreferences putStringSet doesn't work [duplicate]

Answer 1

use edit.clear() before putStringSet

SharedPreferences ss = getSharedPreferences("db", 0);
Set hs = ss.getStringSet("set", new HashSet());
hs.add(String.valueOf(hs.size()+1));
Editor edit = ss.edit();
edit.clear();
edit.putStringSet("set", hs);
edit.commit();