Class to Show the preference screen with Fragment keeping state

MyPreferencesFragmentStateful.java

import android.os.Bundle;
import android.support.annotation.Nullable;
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 Fragment keeping state
 * @author Aaron Vargas
 */
public class MyPreferencesFragmentStateful extends AppCompatActivity {
    private PrefsFragment prefsFragment;

    @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
    public void onBackPressed() {
        // need to delegate the backPress to the fragment since it cannot listen directly
        if (!prefsFragment.onBackPressed()) {
            super.onBackPressed();
        }
    }

    public static class PrefsFragment extends PreferenceFragmentCompat {
        private static final String PREFERENCE_SCREENS = "PREFERENCE_SCREENS";
        private Stack<PreferenceScreen> preferenceScreens = new Stack<>();

        @Override
        public void onNavigateToScreen(PreferenceScreen preferenceScreen) {
            super.onNavigateToScreen(preferenceScreen);
            preferenceScreens.push(getPreferenceScreen());
            setPreferenceScreen(preferenceScreen);
        }

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

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

        @Override
        public void onViewStateRestored(@Nullable Bundle savedInstanceState) {
            super.onViewStateRestored(savedInstanceState);
            if (savedInstanceState == null) return;

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

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

        @Override
        public void onResume() {
            super.onResume();
            // account for onRestore not getting called equally to onSave
            preferenceScreens.remove(getPreferenceScreen());
        }

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

            if (!preferenceScreens.empty()) {
                setPreferenceScreen(preferenceScreens.pop());
                return true; // handled
            } else {
                return false;
            }
        }

        @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);
        }
    }

}