Question

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，框架将在单击时处理它的显示。 http://developer.android.com/guide/topics/ui/settings.html#Subscreens

<PreferenceScreen  xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- opens a subscreen of settings -->
    <PreferenceScreen
        android:key="button_voicemail_category_key"
        android:title="@string/voicemail"
        android:persistent="false">
        <ListPreference
            android:key="button_voicemail_provider_key"
            android:title="@string/voicemail_provider" ... />
        <!-- opens another nested subscreen -->
        <PreferenceScreen
            android:key="button_voicemail_setting_key"
            android:title="@string/voicemail_settings"
            android:persistent="false">
            ...
        </PreferenceScreen>
        <RingtonePreference
            android:key="button_voicemail_ringtone_key"
            android:title="@string/voicemail_ringtone_title"
            android:ringtoneType="notification" ... />
        ...
    </PreferenceScreen>
    ...
</PreferenceScreen>

使用本机Activity，PreferenceFragment可以正常工作......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内容......我是否需要实现任何额外的回调？

编辑：只是为了完整......

这样可以打开子屏幕：

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

在摆弄 support.v7.preference 几天之后，我在这里总结了我的发现，希望它可以帮助其他人： HowTo use support.v7.preference with AppCompat and potential drawbacks

Answer 1

它看起来像PreferenceFragmentCompat中的错误或文档不足。它有onNavigateToScreen方法，当你点击PreferenceScreen项目时会调用它。

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。

<connectionStrings>
  <add 
    name="NorthwindConnectionString" 
    connectionString="Data Source=serverName;Initial 
    Catalog=Northwind;Persist Security Info=True;User 
    ID=userName;Password=password"
    providerName="System.Data.SqlClient"
  />
</connectionStrings>

但是当你无法回到初始的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How to move back from Preferences subscreen to main screen in PreferenceFragmentCompat?

Answer 2

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here

中关注了此问题

官方文档缺少加载首选项子屏幕的文档 - Refer here for official documentation- -

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（自定义图案设置）： -

检查自定义复选框后，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

以下是包含文档的示例代码： -

在res / xml / preferences.xml文件中： -

    <?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    android:summary="Trying intro text">
    <PreferenceCategory android:title="Settings">
        <CheckBoxPreference
            android:defaultValue="true"
            android:key="defaultPress"
            android:title="Default settings" />
        <CheckBoxPreference
            android:defaultValue="false"
            android:key="customKey"
            android:title="Custom" />
        <PreferenceScreen
            android:key="customPrefKey"
            android:title="Custom Pattern Settings">
            <PreferenceCategory
                android:key="customSettingsKey"
                android:title="Custom Settings">
                <ListPreference
                    android:defaultValue="4"
                    android:entries="@array/initialClickArray"
                    android:entryValues="@array/initialClickValues"
                    android:key="initialClicks"
                    android:summary="initialClicksSummary"
                    android:title="No. Of Clicks" />
                <ListPreference
                    android:defaultValue="5"
                    android:entries="@array/initialTimeArray"
                    android:entryValues="@array/initialTimeValues"
                    android:key="initialTimeKey"
                    android:summary="Time to complete clicks"
                    android:title="Time to complete" />
            </PreferenceCategory>
        </PreferenceScreen>
    </PreferenceCategory>
</PreferenceScreen>

MainActivity.java应实现接口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);
    }
}

Answer 3

你需要记住一个非常重要的事情：

您的首选项屏幕必须包含：

android:key="name_a_unique_key"

否则，它将无法正常工作。我已经花了好几个小时了。

Answer 4

覆盖 PreferenceFragmentCompat.OnPreferenceStartScreenCallback

并将以下内容添加到我的偏好片段中保存了我的一天

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

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

我的偏好版本是

compile 'com.android.support:preference-v7:25.0.0'

Answer 5

似乎Google最终决定在新发布的AndroidX首选项1.1.0-alpha中支持此功能。

This video from Android Dev Summit covers something about preference sub screen.

使用support.v7.preference时，首选项子屏幕无法打开

5 个答案: