首选项：当取消选中所有依赖项时，如何取消选中SwitchPreference

Question

我有一个SwitchPreference和两个CheckBoxPreference，它们都是SwitchPreference的依赖项。

我真正想做的是，如果两个CheckBoxPreference都未选中，则应自动取消选中SwitchPreference，但我的代码无效。

这些是我目前正在做的事情：

fragment_settings

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
        <PreferenceCategory
            android:title="@string/set_network">

        <SwitchPreference
            android:defaultValue="true"
            android:key="@string/set_image"
            android:title="@string/set_image"/>

        <CheckBoxPreference
            android:defaultValue="true"
            android:key="@string/set_image_rock"
            android:title="@string/set_image_rock"
            android:dependency="@string/set_image"
            android:summaryOn="@string/enabled"
            android:summaryOff="@string/disabled"/>

        <CheckBoxPreference
            android:defaultValue="true"
            android:key="@string/set_image_rock_details"
            android:title="@string/set_image_rock_details"
            android:dependency="@string/set_image"
            android:summaryOn="@string/enabled"
            android:summaryOff="@string/disabled"/>

    </PreferenceCategory>
</PreferenceScreen>

SettingsFragment

public class SettingsFragment extends PreferenceFragment implements SharedPreferences.OnSharedPreferenceChangeListener{


    public SettingsFragment() {
        // Required empty public constructor
    }

    //private ListPreference mListPreference;
    private SwitchPreference loadImages;
    private CheckBoxPreference rockImages, rockDetailsImages;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view =  inflater.inflate(R.layout.fragment_settings, container, false);
        view.setBackgroundColor(Color.WHITE);

        loadImages = (SwitchPreference) getPreferenceManager().findPreference(getString(R.string.set_image));
        rockImages = (CheckBoxPreference) getPreferenceManager().findPreference(getString(R.string.set_image_rock)););
        return view;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.fragment_settings);
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        if (!rockImages.isChecked() && !rockDetailsImages.isChecked()) {
            loadImages.setChecked(false); //This refuses to happen.
        }
    }
}

请问我该如何实现？