Question

In my application, when the phone is held in portrait mode the filename can be retrieved.

When I rotate the phone, the same file is being used to get the preferences, but this particular preference comes back blank.

I checked the one function where I write to this preference but it isn’t called when the phone is rotated.

So, what could be the cause of a change in the sharedpreferences by rotating the phone?

Here is the code that I use:

static String retrieveStoredFilename(Context context) {
    SharedPreferences myPrefs = context.getSharedPreferences(PREF_NAME,
            Context.MODE_PRIVATE);
    String s = myPrefs.getString(FILENAME, "");

    return TextUtils.isEmpty(s) ? (String) null : s;
}

Here is some more code in case it helps. This is from the fragment that is actually messed up by the rotation. In onResume filename is set to null after rotating, but from then on it is null, even when I rotate back.

@Override
public void onPause() {
    super.onPause();
    mIV.getBitmap().recycle();
    mIV.setImageResource(R.drawable.ic_action_search);
    if (myBitMap != null)
        myBitMap.recycle();
}

@Override
public void onResume() {
    super.onResume();
    filename = ControllerFragment.retrieveStoredFilename(getActivity());
    getBitmap(filename);
    mIV.invalidate();
    }

And the two constants are:

public static String FILENAME = "filename";
public static String PREF_NAME = "photobrowser";

Answer 1

The only possibility that I see is that the value of FILENAME is not being persisted. It may be worth looking into the lifecycle of an Activity and Saving Activity state on Android.

Here is an exert from the android documentation about Configuration Changes.

Unless you specify otherwise, a configuration change (such as a change
in screen orientation, language, input devices, etc) will cause your
current activity to be destroyed, going through the normal activity
lifecycle process of onPause(), onStop(), and onDestroy() as
appropriate. If the activity had been in the foreground or visible to
the user, once onDestroy() is called in that instance then a new
instance of the activity will be created, with whatever
savedInstanceState the previous instance had generated from
onSaveInstanceState(Bundle).

Because of this your onResume() is never called after an orientation change. The activity goes through the entire lifecycle to onDestroy(). After the orientation change onCreate() is called as it is a new instance of your activity.