Class to Show the preference screen with keeping state

MyPreferencesActivityStateful.java

    import android.os.Bundle;
    import android.support.v7.app.AppCompatActivity;
    import android.support.v7.preference.PreferenceFragmentCompat;
    import android.support.v7.preference.PreferenceScreen;

    import java.util.ArrayList;
    import java.util.Objects;
    import java.util.Stack;

    /**
     * Class to Show the preference screen with Activity keeping state
     * @author Aaron Vargas
     */
    public class MyPreferencesActivityStateful extends AppCompatActivity implements PreferenceFragmentCompat.OnPreferenceStartScreenCallback {
        private static final String PREFERENCE_SCREENS = "PREFERENCE_SCREENS";
        private PrefsFragment prefsFragment;
        private Stack<PreferenceScreen> preferenceScreens = new Stack<>();

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            // Display the fragment as the main content. Re-Use if possible
            String tag = PrefsFragment.class.getName();
            prefsFragment = (PrefsFragment) getSupportFragmentManager().findFragmentByTag(tag);
            if (prefsFragment == null) prefsFragment = new PrefsFragment();

            getSupportFragmentManager().beginTransaction().replace(android.R.id.content,
                    prefsFragment, tag).commit();
        }

        @Override
        protected void onRestoreInstanceState(Bundle savedInstanceState) {
            super.onRestoreInstanceState(savedInstanceState);

            // rebuild preferenceScreen stack
            for (String screenKey : Objects.requireNonNull(savedInstanceState.getStringArrayList(PREFERENCE_SCREENS))) {
                preferenceScreens.push((PreferenceScreen) prefsFragment.findPreference(screenKey));
            }

            PreferenceScreen preferenceScreen = preferenceScreens.pop();
            if (preferenceScreen != prefsFragment.getPreferenceScreen()) { // optimize if same
                prefsFragment.setPreferenceScreen(preferenceScreen);
            }
        }

        @Override
        public boolean onPreferenceStartScreen(PreferenceFragmentCompat preferenceFragmentCompat, PreferenceScreen preferenceScreen) {
            preferenceScreens.push(preferenceFragmentCompat.getPreferenceScreen());
            preferenceFragmentCompat.setPreferenceScreen(preferenceScreen);
            return true;
        }

        @Override
        public void onBackPressed() {
            // account for onRestore not getting called equally to onSave
            while (preferenceScreens.contains(prefsFragment.getPreferenceScreen())) {
                preferenceScreens.remove(prefsFragment.getPreferenceScreen());
            }

            if (preferenceScreens.empty()) {
                super.onBackPressed();
            } else {
                prefsFragment.setPreferenceScreen(preferenceScreens.pop());
            }
        }

        @Override
        protected void onSaveInstanceState(Bundle outState) {
            super.onSaveInstanceState(outState);
            preferenceScreens.push(prefsFragment.getPreferenceScreen());

            ArrayList<String> keys = new ArrayList<>(preferenceScreens.size());
            for (PreferenceScreen screen : preferenceScreens) {
                keys.add(screen.getKey());
            }
            outState.putStringArrayList(PREFERENCE_SCREENS, keys);
        }

        public static class PrefsFragment extends PreferenceFragmentCompat {

            @Override
            public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {

                setRetainInstance(true); // ensure in manifest - android:configChanges="orientation"

                // Load the preferences from an XML resource
                setPreferencesFromResource(R.xml.preferences, rootKey);
            }
        }

    }