Symbolleiste wird versteckt in verschachtelten PreferenceScreen

Fand ich die Lösung auf meinem eigenen. Ich habe einen kleinen work-around, der alle diese verschachtelten PreferenceScreen's. Ich machte einfach eine Trennung auf verschiedene xml-preference - Dateien, erstellt einen zusätzlichen Fragment erstreckt PreferenceFragment und dort zeige ich eine entsprechende verschachtelten Bildschirm bevorzugt.

Vielleicht würde jemand fand dies nützlich.

Github Quellen-link.

Einige code-Beispiele unten:

main_preferences.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

    <PreferenceCategory android:title="Main category" >

        <EditTextPreference
            android:defaultValue="defaultValue"
            android:key="key_global_setting"
            android:title="Global title" />

    </PreferenceCategory>

    <PreferenceCategory android:title="Nested screens" >

        <Preference
            android:key="NESTED_KEY1"
            android:persistent="false"
            android:title="Nested screen #1" />

        <Preference
            android:key="NESTED_KEY2"
            android:persistent="false"
            android:title="Nested screen #2" />

    </PreferenceCategory>

</PreferenceScreen> 

nested_screen1_preferences.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    android:title="Nested screen #1" >

    <CheckBoxPreference
        android:defaultValue="false"
        android:key="nested_screen_1_1"
        android:title="Nested screen 1.1 check box" />

    <CheckBoxPreference
        android:defaultValue="true"
        android:key="nested_screen_1_2"
        android:title="Nested screen 1.2 check box" />
</PreferenceScreen>

nested_screen2_preferences.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    android:title="Nested screen #2">

    <CheckBoxPreference
        android:defaultValue="true"
        android:key="nested_screen2"
        android:title="Nested screen 2 check box" />
</PreferenceScreen>

SettingsActivity.java

public class SettingsActivity extends ActionBarActivity implements MyPreferenceFragment.Callback {

    private static final String TAG_NESTED = "TAG_NESTED";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_settings);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        if (toolbar != null) {
            setSupportActionBar(toolbar);
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        }

        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.contentSettings, new MyPreferenceFragment())
                    .commit();
        }
    }

    @Override
    public void onBackPressed() {
        //this if statement is necessary to navigate through nested and main fragments
        if (getFragmentManager().getBackStackEntryCount() == 0) {
            super.onBackPressed();
        } else {
            getFragmentManager().popBackStack();
        }
    }

    @Override
    public void onNestedPreferenceSelected(int key) {
        getFragmentManager().beginTransaction().replace(R.id.contentSettings, NestedPreferenceFragment.newInstance(key), TAG_NESTED).addToBackStack(TAG_NESTED).commit();
    }    
}

MyPreferenceFragment.java

//The main preference fragment class
public class MyPreferenceFragment extends PreferenceFragment implements Preference.OnPreferenceClickListener {

    private Callback mCallback;

    private static final String KEY_1 = "NESTED_KEY1";
    private static final String KEY_2 = "NESTED_KEY2";

    @Override
    public void onAttach(Activity activity) {

        super.onAttach(activity);

        if (activity instanceof Callback) {
            mCallback = (Callback) activity;
        } else {
            throw new IllegalStateException("Owner must implement Callback interface");
        }
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //Load the preferences from an XML resource
        addPreferencesFromResource(R.xml.main_preferences);

        //add listeners for non-default actions
        Preference preference = findPreference(KEY_1);
        preference.setOnPreferenceClickListener(this);

        preference = findPreference(KEY_2);
        preference.setOnPreferenceClickListener(this);
    }

    @Override
    public boolean onPreferenceClick(Preference preference) {
        //here you should use the same keys as you used in the xml-file
        if (preference.getKey().equals(KEY_1)) {
            mCallback.onNestedPreferenceSelected(NestedPreferenceFragment.NESTED_SCREEN_1_KEY);
        }

        if (preference.getKey().equals(KEY_2)) {
            mCallback.onNestedPreferenceSelected(NestedPreferenceFragment.NESTED_SCREEN_2_KEY);
        }

        return false;
    }

    public interface Callback {
        public void onNestedPreferenceSelected(int key);
    }
}

NestedPreferencesFragment.java

public class NestedPreferenceFragment extends PreferenceFragment {

    public static final int NESTED_SCREEN_1_KEY = 1;
    public static final int NESTED_SCREEN_2_KEY = 2;

    private static final String TAG_KEY = "NESTED_KEY";

    public static NestedPreferenceFragment newInstance(int key) {
        NestedPreferenceFragment fragment = new NestedPreferenceFragment();
        //supply arguments to bundle.
        Bundle args = new Bundle();
        args.putInt(TAG_KEY, key);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        checkPreferenceResource();
    }

    private void checkPreferenceResource() {
        int key = getArguments().getInt(TAG_KEY);
        //Load the preferences from an XML resource
        switch (key) {
            case NESTED_SCREEN_1_KEY:
                addPreferencesFromResource(R.xml.nested_screen1_preferences);
                break;

            case NESTED_SCREEN_2_KEY:
                addPreferencesFromResource(R.xml.nested_screen2_preferences);
                break;

            default:
                break;
        }
    }

}

In meiner Lösung braucht man nur AppCompatActivity und eine PreferenceFragement, aber mehrere XML-Dateien, die jeweils nur eine Ebene der PreferenceScreens.

XML-Datei Liste

• top-level-PreferenceScreen
• zweiten Ebene PreferenceScreen 0
• zweiten Ebene PreferenceScreen 1
• zweiten Ebene PreferenceScreen 2
• ...

Dieser code ist für eine sub-Ebene (für die Schlichtheit und Sie erhalten die Idee), aber Sie können leicht erweitern, um beliebige sub-Ebenen der PreferenceScreens.

SettingsFragment.java

public class SettingsFragment extends PreferenceFragment
{
    private int xmlId;

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

    public void changePrefScreen(int xmlId, int titleId)
    {
        this.xmlId = xmlId;
        ((AppCompatActivity)getActivity()).getSupportActionBar().setTitle(getActivity().getResources().getString(titleId));
        getPreferenceScreen().removeAll();
        addPreferencesFromResource(xmlId);
    }

    //will be called by SettingsActivity (Host Activity)
    public void onUpButton()
    {
        if(xmlId == R.xml.preferences) //in top-level
        {
            //Switch to MainActivity
            Intent intent = new Intent(getActivity(), MainActivity.class);
            startActivity(intent);
        }
        else //in sub-level
        {
            changePrefScreen(R.xml.preferences, R.string.settings);
        }
    }

    @Override
    public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference)
    {
        String key = preference.getKey();

        //
        //Top level PreferenceScreen
        //
        if(key.equals("top_key_0"))
        {
            changePrefScreen(R.xml.download_preference_screen, R.string.download_database); //descend into second level
        }

        //...

        //
        //Second level PreferenceScreens
        //
        if (key.equals("second_level_key_0"))
        {
           //do something...
        }

        //...
     }

SettingsActivity.java

public class SettingsActivity extends AppCompatActivity
{
    SettingsFragment settingsFragment;

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

        settingsFragment = new SettingsFragment();

        //Display the fragment as the main content.
        getFragmentManager().beginTransaction()
                .replace(android.R.id.content, settingsFragment)
                .commit();
    }

    //
    //Handle what happens on up button
    //
    @Override
    public boolean onOptionsItemSelected(MenuItem item) 
    {
        switch (item.getItemId()) 
        {
            case android.R.id.home:
                settingsFragment.onUpButton();
                return true;
        }
        return true;
    }

    //...
}

Technisch sollte es Arbeit für alle Android-Versionen, für die die PreferenceFragment verfügbar ist.