SavedPreferences does not save

Question

I am playing around a bit with android's SharedPreferences.

See my code:

@Override
    public void onPause() {
       super.onPause();
       SharedPreferences prefs = this.getSharedPreferences(
        "com.example.app", Context.MODE_PRIVATE);
         for (int i = 0; i<meds.size(); i++){
         prefs.edit().putString(String.valueOf(i), meds.get(i));
         System.out.println(meds.get(i));
         String str = prefs.getString("0", "");
         System.out.println(str);
         System.out.println(i);


    }


        prefs.edit().commit();




  }

Now I get all the prints except for that which is supposed to print str. I take it nothing is saved.

But why is that?

Answer 1

Note that prefs.edit() returns a new editor on the shared prefernces. If you do prefs.edit().commit(); the commit operates on a new editor object. You have to store a reference to the editor like that:

@Override
public void onPause() {
    super.onPause();
    SharedPreferences prefs = this.getSharedPreferences(
        "com.example.app", Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = prefs.edit();
    for (int i = 0; i<meds.size(); i++){
        editor.putString(String.valueOf(i), meds.get(i));
        System.out.println(meds.get(i));
        String str = prefs.getString("0", "");
        System.out.println(str);
        System.out.println(i);
    }
    editor.commit();
}

Otherwise nothing is saved.

Answer 2

commit after putting.

@Override
    public void onPause() {
       super.onPause();
       SharedPreferences prefs = this.getSharedPreferences(
        "com.example.app", Context.MODE_PRIVATE);
         for (int i = 0; i<meds.size(); i++){
         prefs.edit().putString(String.valueOf(i), meds.get(i)).commit();
         System.out.println(meds.get(i));
         String str = prefs.getString("0", "");
         System.out.println(str);
         System.out.println(i);


    }

Answer 3

Commit after putting a String in Preferences

Corrected Code:

@Override
public void onPause() {
super.onPause();
SharedPreferences prefs = this.getSharedPreferences(
    "com.example.app", Context.MODE_PRIVATE);

SharedPreferences.Editor editor = prefs.edit();

for (int i = 0; i<meds.size(); i++){
    editor.putString(String.valueOf(i), meds.get(i));
    System.out.println(meds.get(i));
    String str = prefs.getString("0", "");
    System.out.println(str);
    System.out.println(i);
}

editor.commit();
}

Answer 4

try like this,

@Override
    public void onPause() {
       super.onPause();
       SharedPreferences prefs = this.getSharedPreferences(
        "com.example.app", Context.MODE_PRIVATE);
         for (int i = 0; i<meds.size(); i++){
         prefs.edit().putString(String.valueOf(i), meds.get(i));
         System.out.println(meds.get(i));

         System.out.println(str);
         System.out.println(i);


    }


        prefs.edit().commit();


 String str = prefs.getString("0", "");

  }