How to move back from Preferences subscreen to main screen in PreferenceFragmentCompat?

Question

I am trying to implement a Settings screen using PreferenceFragmentCompat. My preference xml has a preference subscreen like this:

preferences.xml

Answer 1

I have added a complete working example with screenshots and code snippets here in this post, I hope this will be helpful to someone.

It covers following scenarios:-- 1) A main setting screen with two checkboxes and a subscreen title. 2) On click of subscreen title, the new preference subscreen opens. 3) On back pressed, the control goes to main Settings screen. So the back press is handled properly.

The MainActivity looks like this(overridden onPreferenceStartScreen method handles the opening of new subscreen in a new window):--

  public class MainActivity extends AppCompatActivity implements PreferenceFragmentCompat.OnPreferenceStartScreenCallback {

    private static final String TAG = MainActivity.class.getName();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        FragmentManager fragmentManager = getSupportFragmentManager();
        Fragment fragment = null;
        if (savedInstanceState == null) {
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragment = new AdvancedSettingsFragment().newInstance("Advanced Setting");
            fragmentTransaction.add(R.id.fragment_container, fragment);
            fragmentTransaction.commit();
        }
    }

    @Override
        public boolean onPreferenceStartScreen(PreferenceFragmentCompat preferenceFragmentCompat,
                                           PreferenceScreen preferenceScreen) {
        Log.d(TAG, "callback called to attach the preference sub screen");
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        AdvancedSettingsSubScreenFragment fragment = AdvancedSettingsSubScreenFragment.newInstance("Advanced Settings Subscreen");
        Bundle args = new Bundle();
        //Defining the sub screen as new root for the  subscreen
        args.putString(PreferenceFragmentCompat.ARG_PREFERENCE_ROOT, preferenceScreen.getKey());
        fragment.setArguments(args);
        ft.replace(R.id.fragment_container, fragment, preferenceScreen.getKey());
        ft.addToBackStack(null);
        ft.commit();
        return true;
    }

and finally the in subscreen fragment setPreferencesFromResource(R.xml.preferences, rootKey); handles the attachment of subscreen to the rootkey.

public class AdvancedSettingsSubScreenFragment extends PreferenceFragmentCompat {
    private static final String TAG = AdvancedSettingsSubScreenFragment.class.getName();
    public static final String PAGE_ID = "page_id";

    public static AdvancedSettingsSubScreenFragment newInstance(String pageId) {
        AdvancedSettingsSubScreenFragment f = new AdvancedSettingsSubScreenFragment();
        Bundle args = new Bundle();
        args.putString(PAGE_ID, pageId);
        f.setArguments(args);
        return (f);
    }

    @Override
    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
        // rootKey is the name of preference sub screen key name , here--customPrefKey
        setPreferencesFromResource(R.xml.preferences, rootKey);
        Log.d(TAG, "onCreatePreferences of the sub screen " + rootKey);
    }
}