使用support.v7.preference时,首选项子屏幕无法打开

我正在尝试使用AppCompatActivity和support.v7.preference在子屏幕上实现首选项

根据文档,另一个PreferenceScreen中的每个PreferenceScreen都用作子屏幕,框架将处理单击时显示它. http://developer.android.com/guide/topics/ui/settings.html#Subscreens

    
    
        
        
        
            ...
        
        
        ...
    
    ...

这可以使用本机Activity,PreferenceFragment工作正常...但是使用AppCompatActivity和PreferenceFragmentCompat,单击Preference元素只会突出显示它,但不会打开子屏幕.

我在这个文档和代码上找不到任何东西......我需要实现任何额外的回调吗？

编辑:只是为了完整...

这可以工作并打开子屏幕:

public class MainActivity extends Activity {

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

        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .replace(android.R.id.content, new DemoPreferenceFragment())
                    .commit();
        }
    }

    static public class DemoPreferenceFragment extends PreferenceFragment {

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

这不起作用/打开子屏幕:

public class MainActivity extends AppCompatActivity {

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

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .replace(android.R.id.content, new DemoPreferenceFragment())
                    .commit();
        }
    }

    static public class DemoPreferenceFragment extends PreferenceFragmentCompat {

        @Override
        public void onCreatePreferences(Bundle bundle, String s) {
            addPreferencesFromResource(R.xml.preferences);
        }
    }
}

编辑:2016年1月25日

在使用support.v7.preference几天后,我总结了我的发现,希望它可以帮助其他人:如何 使用Support.v7.preference与AppCompat和潜在的缺点

它看起来像PreferenceFragmentCompat中的错误或docs的不足.它具有onNavigateToScreen方法,当您单击PreferenceScreen项时调用该方法.

但是方法getCallbackFragment()默认返回null,因此您需要在片段中覆盖它以返回它.您还需要实现PreferenceFragmentCompat.OnPreferenceStartScreenCallback.

public class SettingsFragment extends PreferenceFragmentCompat implements PreferenceFragmentCompat.OnPreferenceStartScreenCallback {

    public static SettingsFragment newInstance() {
        return new SettingsFragment();
    }

    @Override
    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
        addPreferencesFromResource(R.xml.news_settings);
    }

    @Override
    public Fragment getCallbackFragment() {
        return this;
    }

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

但是当你无法回到最初的PreferenceScreen时会导致另一个问题,

另一种方法是替换此处描述的片段如何从PreferenceFragmentCompat中的Preferences子屏幕移回主屏幕？

这是完整的工作示例,我希望这对某人有帮助.它包括打开首选项子屏幕并返回主设置屏幕.

我在Android开源问题跟踪器中关注了这个问题 - 这里

官方文档缺少加载首选项子屏幕的文档 - 请参阅此处获取官方文档 -

主要高级设置屏幕有2个复选框和一个禁用的子屏幕标题(自定义模式设置): -

检查"自定义"复选框后,将启用子屏幕标题.

单击自定义图案设置后,子屏幕将在新屏幕中打开

以下是带有文档的示例代码: -

在res/xml/preferences.xml文件中: -

MainActivity.java应该实现接口PreferenceFragmentCompat.OnPreferenceStartScreenCallback然后覆盖方法 -onPreferenceStartScreen

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;
    }

对于主设置屏幕(片段): -

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

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

    @Override
    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
        // Load the preferences from an XML resource
        addPreferencesFromResource(R.xml.preferences);
        final CheckBoxPreference customPreference = (CheckBoxPreference) findPreference("customKey");
        final Preference customSettings = (Preference) findPreference("customPrefKey");
        // First time loading the preference screen, we check the saved settings and enable/disable the custom settings, based on the custom check box
        //get the customSettings value from shared preferences
        if (getCustomSettings(getActivity())) {
            customPreference.setChecked(true);
            customSettings.setEnabled(true);
        } else {
            customPreference.setChecked(false);
            customSettings.setEnabled(false);
        }
        customPreference.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
            @Override
            public boolean onPreferenceChange(Preference preference, Object selectedValue) {
                Log.d(TAG, "Inside on preference change of custom checkbox selection " + selectedValue.getClass());
                if ((Boolean) selectedValue) {
                    customSettings.setEnabled(true);
                }else{
                    customSettings.setEnabled(false);
                }
                return true;
            }
        });
    }
    private boolean getCustomSettings(Context context) {
        return PreferenceManager.getDefaultSharedPreferences(getActivity()).getBoolean("customKey", false);
    }
}

最后加载子屏幕:

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);
    }
}