Скрыть опцию из списка предпочтений

Question

У меня есть совершенно незавершенный проект андроида, параметры которого имеют предпочтение списка. То, что я хочу сделать, - навсегда скрыть параметр черного списка символов из списка, но он будет работать внутри. Для этого я сделал

<EditTextPreference android:key="preference_character_blacklist" 
     android:title="Character blacklist" 
     android:visibility="gone"/> 

но это не сработало. Скорее это показало ошибку, когда я пошел в настройки после запуска проекта. Настройки выглядеть следующим образом-файл: ///home/Piyal/Desktop/Screenshot.png мой preference.xml

это-

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> 

<!-- GENERAL SETTINGS --> 
<PreferenceCategory android:title="General settings"> 

    <CheckBoxPreference android:key="preference_capture_continuous" 
     android:title="Continuous preview" 
     android:entries="@array/capturemodes" /> 

    <ListPreference android:title="Recognize" 
     android:key="sourceLanguageCodeOcrPref" 
     android:entries="@array/languagenames" 
     android:entryValues="@array/iso6393" /> 

</PreferenceCategory> 

<!-- TRANSLATION SETTINGS --> 
<PreferenceCategory android:title="Translation settings" 
        > 

    <CheckBoxPreference android:key="preference_translation_toggle_translation" 
     android:title="Translate"/> 

    <ListPreference android:key="targetLanguageCodeTranslationPref" 
     android:title="Translate to" 
     android:dependency="preference_translation_toggle_translation" 
     android:entries="@array/translationtargetlanguagenames_google" 
     android:entryValues="@array/translationtargetiso6391_google" /> 

    <ListPreference android:key="preference_translator" 
     android:title="Translator" 
     android:dependency="preference_translation_toggle_translation" 
     android:entries="@array/translators" 
     android:entryValues="@array/translators" 

     /> 


</PreferenceCategory> 

<!-- ADVANCED SETTINGS --> 
<PreferenceCategory android:title="Advanced settings"> 

    <ListPreference android:key="preference_ocr_engine_mode" 
     android:title="OCR engine" 
     android:entries="@array/ocrenginemodes" 
     android:entryValues="@array/ocrenginemodes"/> 

    <ListPreference android:key="preference_operator_mode" 
     android:title="Operator" 
     android:entries="@array/operatormodes" 
     android:entryValues="@array/operatormodes" 
     /> 

    <CheckBoxPreference 
     android:key="preferences_auto_focus" 
     android:title="Autofocus"/> 

    <CheckBoxPreference 
     android:key="preferences_play_beep" 
     android:title="Beep"/> 

    <EditTextPreference android:key="preference_character_blacklist" 
     android:title="Character blacklist"/> 

    <EditTextPreference 

     android:key="preference_character_whitelist" 
     android:title="Character whitelist" 

     /> 


<!-- 
    <CheckBoxPreference 
     android:key="preference_toggle_light" 
     android:title="Light"/> 
--> 

    <ListPreference android:key="preference_page_segmentation_mode" 
     android:title="Page segmentation" 
     android:entries="@array/pagesegmentationmodes" 
     android:entryValues="@array/pagesegmentationmodes" /> 

    <CheckBoxPreference 
     android:key="preferences_reverse_image" 
     android:title="Reversed camera image" 
     android:summary="(For devices with only a front camera)"/> 

</PreferenceCategory> 

    </PreferenceScreen>` 

Вот мой preferenceacitivity-

public class PreferencesActivity extends PreferenceActivity implements 
    OnSharedPreferenceChangeListener { 

    // Preference keys not carried over from R.M Theis project project 
    public static final String KEY_OPERATOR_MODE = "preference_operator_mode"; 


    // Preference keys not carried over from ZXing project 
    public static final String KEY_SOURCE_LANGUAGE_PREFERENCE = 

    "sourceLanguageCodeOcrPref"; 
    public static final String KEY_TARGET_LANGUAGE_PREFERENCE = 

"targetLanguageCodeTranslationPref"; 
    public static final String KEY_TOGGLE_TRANSLATION = 

"preference_translation_toggle_translation"; 
    public static final String KEY_CONTINUOUS_PREVIEW = 

"preference_capture_continuous"; 
    public static final String KEY_PAGE_SEGMENTATION_MODE = 

"preference_page_segmentation_mode"; 
    public static final String KEY_OCR_ENGINE_MODE = "preference_ocr_engine_mode"; 
    public static final String KEY_CHARACTER_BLACKLIST = 

"preference_character_blacklist"; 
    public static final String KEY_CHARACTER_WHITELIST = 

"preference_character_whitelist"; 
    public static final String KEY_TOGGLE_LIGHT = "preference_toggle_light"; 
    public static final String KEY_TRANSLATOR = "preference_translator"; 

    // Preference keys carried over from ZXing project 
    public static final String KEY_AUTO_FOCUS = "preferences_auto_focus"; 
    public static final String KEY_HELP_VERSION_SHOWN = 

"preferences_help_version_shown"; 
    public static final String KEY_NOT_OUR_RESULTS_SHOWN = 

"preferences_not_our_results_shown"; 
    public static final String KEY_REVERSE_IMAGE = "preferences_reverse_image"; 
    public static final String KEY_PLAY_BEEP = "preferences_play_beep"; 
    public static final String KEY_VIBRATE = "preferences_vibrate"; 

    public static final String TRANSLATOR_BING = "Bing Translator"; 
    public static final String TRANSLATOR_GOOGLE = "Google Translate"; 

    //private CheckBoxPreference checkBoxPreferenceContinuousPreview; 
    private ListPreference listPreferenceSourceLanguage; 
    //private CheckBoxPreference checkBoxTranslate; 
    private ListPreference listPreferenceTargetLanguage; 
    private ListPreference listPreferenceTranslator; 
    private ListPreference listPreferenceOcrEngineMode; 
    //private CheckBoxPreference checkBoxBeep; 
    private EditTextPreference editTextPreferenceCharacterBlacklist; 
    private EditTextPreference editTextPreferenceCharacterWhitelist; 
    private ListPreference listPreferencePageSegmentationMode; 
    //private CheckBoxPreference checkBoxReversedImage; 

    private ListPreference listPreferenceOperatorMode; 

    private static SharedPreferences sharedPreferences; 

    /** 
    * Set the default preference values. 
    * 
    * @param Bundle 
    *   savedInstanceState the current Activity's state, as passed by 
    *   Android 
    */ 
    @Override 
    protected void onCreate(Bundle savedInstanceState) 
    { 
    super.onCreate(savedInstanceState); 
    getWindow().setBackgroundDrawableResource(R.drawable.background_holo_dark); 
    addPreferencesFromResource(R.xml.preferences); 

    sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this); 

    //checkBoxPreferenceContinuousPreview = (CheckBoxPreference) 

getPreferenceScreen().findPreference(KEY_CONTINUOUS_PREVIEW); 
    listPreferenceSourceLanguage = (ListPreference) 

getPreferenceScreen().findPreference(KEY_SOURCE_LANGUAGE_PREFERENCE); 
    //checkBoxTranslate = (CheckBoxPreference) 

getPreferenceScreen().findPreference(KEY_TOGGLE_TRANSLATION); 
    listPreferenceTargetLanguage = (ListPreference) 

getPreferenceScreen().findPreference(KEY_TARGET_LANGUAGE_PREFERENCE); 
    listPreferenceTranslator = (ListPreference) 

getPreferenceScreen().findPreference(KEY_TRANSLATOR);  
    listPreferenceOcrEngineMode = (ListPreference) 

getPreferenceScreen().findPreference(KEY_OCR_ENGINE_MODE); 
    listPreferenceOperatorMode = (ListPreference) 

getPreferenceScreen().findPreference(KEY_OPERATOR_MODE); 

    //checkBoxBeep = (CheckBoxPreference) 

getPreferenceScreen().findPreference(KEY_PLAY_BEEP); 
    editTextPreferenceCharacterBlacklist = (EditTextPreference) 
getPreferenceScreen().findPreference(KEY_CHARACTER_BLACKLIST); 
    editTextPreferenceCharacterWhitelist = (EditTextPreference) 
getPreferenceScreen().findPreference(KEY_CHARACTER_WHITELIST); 
    listPreferencePageSegmentationMode = (ListPreference) 
getPreferenceScreen().findPreference(KEY_PAGE_SEGMENTATION_MODE); 
    //checkBoxReversedImage = (CheckBoxPreference) 
getPreferenceScreen().findPreference(KEY_REVERSE_IMAGE); 

    // Create the entries/entryvalues for the translation target language list. 
    initTranslationTargetList(); 

    } 

    /** 
    * Interface definition for a callback to be invoked when a shared 
    * preference is changed. Sets summary text for the app's preferences. Summary 
text values show the 
    * current settings for the values. 
    * 
    * @param sharedPreferences 
    *   the Android.content.SharedPreferences that received the change 
    * @param key 
    *   the key of the preference that was changed, added, or removed 
    */ 
    @Override 
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, 
     String key) {  
    // Update preference summary values to show current preferences 
    if (key.equals(KEY_TRANSLATOR)) { 
     listPreferenceTranslator.setSummary(sharedPreferences.getString(key, 
CaptureActivity.DEFAULT_TRANSLATOR)); 
    } else if(key.equals(KEY_SOURCE_LANGUAGE_PREFERENCE)) { 

     // Set the summary text for the source language name 

    listPreferenceSourceLanguage. 
setSummary(LanguageCodeHelper.getOcrLanguageName(getBaseContext(), 
sharedPreferences.getString(key,   
CaptureActivity.DEFAULT_SOURCE_LANGUAGE_CODE))); 

     // Retrieve the character blacklist/whitelist for the new language 
     String blacklist = OcrCharacterHelper.getBlacklist(sharedPreferences, 
listPreferenceSourceLanguage.getValue()); 
     String whitelist = OcrCharacterHelper.getWhitelist(sharedPreferences, 
listPreferenceSourceLanguage.getValue()); 

     // Save the character blacklist/whitelist to preferences 
     sharedPreferences.edit().putString(KEY_CHARACTER_BLACKLIST, 
blacklist).commit(); 
     sharedPreferences.edit().putString(KEY_CHARACTER_WHITELIST, 
whitelist).commit(); 

     // Set the blacklist/whitelist summary text 
     editTextPreferenceCharacterBlacklist.setSummary(blacklist); 
     editTextPreferenceCharacterWhitelist.setSummary(whitelist); 

    } else if (key.equals(KEY_TARGET_LANGUAGE_PREFERENCE)) { 

listPreferenceTargetLanguage. 
setSummary(LanguageCodeHelper.getTranslationLanguageName(this, 
sharedPreferences.getString(key,   
CaptureActivity.DEFAULT_TARGET_LANGUAGE_CODE))); 
     } else if (key.equals(KEY_PAGE_SEGMENTATION_MODE)) { 

listPreferencePageSegmentationMode.setSummary(sharedPreferences.getString(key, 
CaptureActivity.DEFAULT_PAGE_SEGMENTATION_MODE)); 
    } else if (key.equals(KEY_OCR_ENGINE_MODE)) { 
     listPreferenceOcrEngineMode.setSummary(sharedPreferences.getString(key, 
CaptureActivity.DEFAULT_OCR_ENGINE_MODE)); 
    } 
    else if (key.equals(KEY_OPERATOR_MODE)) 
    { 
     listPreferenceOperatorMode.setSummary(sharedPreferences.getString(key, 
CaptureActivity.DEFAULT_OPERATOR_MODE)); 
    } 
    else if (key.equals(KEY_CHARACTER_BLACKLIST)) { 

     // Save a separate, language-specific character blacklist for this language 
     OcrCharacterHelper.setBlacklist(sharedPreferences, 
      listPreferenceSourceLanguage.getValue(), 
      sharedPreferences.getString(key, 
OcrCharacterHelper.getDefaultBlacklist(listPreferenceSourceLanguage.getValue()))); 

     // Set the summary text 
    editTextPreferenceCharacterBlacklist. 
setSummary(sharedPreferences.getString(key, 
OcrCharacterHelper.getDefaultBlacklist(listPreferenceSourceLanguage.getValue()))); 

    } else if (key.equals(KEY_CHARACTER_WHITELIST)) { 

     // Save a separate, language-specific character blacklist for this language 
     OcrCharacterHelper.setWhitelist(sharedPreferences, 
      listPreferenceSourceLanguage.getValue(), 
      sharedPreferences.getString(key, 
OcrCharacterHelper.getDefaultWhitelist(listPreferenceSourceLanguage.getValue()))); 

     // Set the summary text 
     editTextPreferenceCharacterWhitelist. 
setSummary(sharedPreferences.getString(key, 
OcrCharacterHelper.getDefaultWhitelist 
(listPreferenceSourceLanguage.getValue()))); 

    } 

    // Update the languages available for translation based on the current 
translator selected. 
    if (key.equals(KEY_TRANSLATOR)) { 
     initTranslationTargetList(); 
    } 

    } 

    /** 
    * Sets the list of available languages and the current target language for 
translation. Called 
    * when the key for the current translator is changed. 
    */ 
    void initTranslationTargetList() { 
    // Set the preference for the target language code, in case we've just 
switched from Google 
    // to Bing, or Bing to Google. 
    String currentLanguageCode = 
sharedPreferences.getString(KEY_TARGET_LANGUAGE_PREFERENCE, 
     CaptureActivity.DEFAULT_TARGET_LANGUAGE_CODE); 

    // Get the name of our language 
    String currentLanguage = 
LanguageCodeHelper.getTranslationLanguageName(getBaseContext(), 
     currentLanguageCode); 
    String[] translators = getResources().getStringArray(R.array.translators); 
    String translator = sharedPreferences.getString(KEY_TRANSLATOR, 
CaptureActivity.DEFAULT_TRANSLATOR); 
    String newLanguageCode = ""; 
    if (translator.equals(translators[0])) { // Bing 
     // Update the list of available languages for the currently-chosen 
translation API. 

listPreferenceTargetLanguage. 
setEntries(R.array.translationtargetlanguagenames_microsoft); 
     listPreferenceTargetLanguage. 
setEntryValues(R.array.translationtargetiso6391_microsoft); 

     // Get the corresponding code for our language name 
     newLanguageCode = TranslatorBing.toLanguage(currentLanguage); 
    } else if (translator.equals(translators[1])) { // Google 
     // Update the list of available languages for the currently-chosen 
translation API. 
     listPreferenceTargetLanguage. 
setEntries(R.array.translationtargetlanguagenames_google); 
     listPreferenceTargetLanguage. 
setEntryValues(R.array.translationtargetiso6391_google); 

     // Get the corresponding code for our language name  
     newLanguageCode = TranslatorGoogle.toLanguage(currentLanguage); 
    } 

    // Store the code as the target language preference 
    String newLanguageName = LanguageCodeHelper. 
getTranslationLanguageName(getBaseContext(), 
     newLanguageCode); 
    listPreferenceTargetLanguage. 
setValue(newLanguageName); // Set the radio button in the list 

sharedPreferences.edit().putString(PreferencesActivity.KEY_TARGET_LANGUAGE_PREFERENCE, 
     newLanguageCode).commit(); 
    listPreferenceTargetLanguage.setSummary(newLanguageName); 
    } 

    /** 
    * Sets up initial preference summary text 
    * values and registers the OnSharedPreferenceChangeListener. 
    */ 
    @Override 
    protected void onResume() { 
    super.onResume(); 
    // Set up the initial summary values 
    listPreferenceTranslator. 
setSummary(sharedPreferences.getString(KEY_TRANSLATOR, 
CaptureActivity.DEFAULT_TRANSLATOR)); 
    listPreferenceSourceLanguage. 
setSummary(LanguageCodeHelper.getOcrLanguageName(getBaseContext(), 
sharedPreferences.getString  
(KEY_SOURCE_LANGUAGE_PREFERENCE, CaptureActivity.DEFAULT_SOURCE_LANGUAGE_CODE))); 
    listPreferenceTargetLanguage. 
setSummary(LanguageCodeHelper.getTranslationLanguageName(getBaseContext(), 
sharedPreferences.getString 
(KEY_TARGET_LANGUAGE_PREFERENCE, CaptureActivity.DEFAULT_TARGET_LANGUAGE_CODE))); 
    listPreferencePageSegmentationMode. 
setSummary(sharedPreferences.getString(KEY_PAGE_SEGMENTATION_MODE, 
    CaptureActivity.DEFAULT_PAGE_SEGMENTATION_MODE)); 
    listPreferenceOcrEngineMode. 
setSummary(sharedPreferences.getString(KEY_OCR_ENGINE_MODE, 
CaptureActivity.DEFAULT_OCR_ENGINE_MODE)); 
    listPreferenceOperatorMode. 
setSummary(sharedPreferences.getString(KEY_OPERATOR_MODE, 
CaptureActivity.DEFAULT_OPERATOR_MODE)); 
    editTextPreferenceCharacterBlacklist. 
setSummary(sharedPreferences.getString(KEY_CHARACTER_BLACKLIST,  
OcrCharacterHelper.getDefaultBlacklist(listPreferenceSourceLanguage.getValue()))); 
    editTextPreferenceCharacterWhitelist. 
setSummary(sharedPreferences.getString 
(KEY_CHARACTER_WHITELIST,OcrCharacterHelper.getDefaultWhitelist 
(listPreferenceSourceLanguage.getValue()))); 

    // Set up a listener whenever a key changes 
    getPreferenceScreen(). 
getSharedPreferences().registerOnSharedPreferenceChangeListener(this); 
    } 

    /** 
    * Called when Activity is about to lose focus. Unregisters the 
    * OnSharedPreferenceChangeListener. 
    */ 
    @Override 
    protected void onPause() { 
    super.onPause(); 
    getPreferenceScreen(). 
getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this); 
    } 
}  

`

Трассировка стека после добавления getPreferenceScreen(). RemovePreference (editTextPreferenceCharacterBlacklist);

in onCreate().

05-30 17:42:00.546: E/AndroidRuntime(379): FATAL EXCEPTION: main 

05-30 17:42:00.546: E/AndroidRuntime(379): java.lang.RuntimeException: Unable to start 
activity 
ComponentInfo{automated.card.recharge.ocr/automated.card. 
recharge.ocr.PreferencesActivity}: java.lang.NullPointerException 
05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.ActivityThread.access$1500(ActivityThread.java:117) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.os.Handler.dispatchMessage(Handler.java:99) 

05-30 17:42:00.546: E/AndroidRuntime(379): at android.os.Looper.loop(Looper.java:123) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.ActivityThread.main(ActivityThread.java:3683) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
java.lang.reflect.Method.invokeNative(Native Method) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
java.lang.reflect.Method.invoke(Method.java:507) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 

05-30 17:42:00.546: E/AndroidRuntime(379): at dalvik.system.NativeStart.main(Native 
Method) 

05-30 17:42:00.546: E/AndroidRuntime(379): Caused by: java.lang.NullPointerException 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.preference.PreferenceGroup.removePreferenceInt(PreferenceGroup.java:181) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 

android.preference.PreferenceGroup.removePreference(PreferenceGroup.java:174) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
automated.card.recharge.ocr.PreferencesActivity.onCreate(PreferencesActivity.java:103) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 

05-30 17:42:00.546: E/AndroidRuntime(379): at dalvik.system.NativeStart.main(Native 
Method) 

05-30 17:42:00.546: E/AndroidRuntime(379): Caused by: java.lang.NullPointerException 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.preference.PreferenceGroup.removePreferenceInt(PreferenceGroup.java:181) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.preference.PreferenceGroup.removePreference(PreferenceGroup.java:174) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
automated.card.recharge.ocr.PreferencesActivity.onCreate(PreferencesActivity.java:103) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 

05-30 17:42:00.546: E/AndroidRuntime(379): at 
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 

Answer 1

Вы должны быть в состоянии удалить:

<EditTextPreference android:key="preference_character_blacklist" 
     android:title="Character blacklist" 
     android:visibility="gone"/> 

от вашего preferences.xml. Это перестанет отображаться в меню «Настройки».

Для того, чтобы работать внутри, я бы предложил прочитать в SharedPreferences. Android Storage Options Guide объяснит, как вы можете сохранить и получить установочные значения с помощью SharedPreferences.

Я изменил следующий пример, чтобы сохранить строку из руководства, связанного выше:

public class Calc extends Activity { 
    public static final String PREFS_NAME = "MyPrefsFile"; 

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

     // Restore preferences 
     SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0); 
     String silent = settings.getString("character_blacklist", ""); 
    } 

    @Override 
    protected void onStop(){ 
     super.onStop(); 

     // We need an Editor object to make preference changes. 
     // All objects are from android.context.Context 
     SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0); 
     SharedPreferences.Editor editor = settings.edit(); 
     //Some test characters for the blacklist 
     mBlackListChars = "a,g,t,h,f"; 
     editor.putString("character_blacklist", mBlackListChars); 

     // Commit the edits 
     editor.commit(); 
    } 
} 

Пожалуйста, обратите внимание, вы, вероятно, хотите, чтобы вызывать эти методы вне onCreate() и onStop(), это чисто для иллюстрации. Кроме того, я обращу ваше внимание на то, что SharedPreferences может обрабатывать StringSet, который может быть вам полезен при хранении нескольких символов. См. Метод getStringSet() в SharedPreferences.

UPDATE

Для того, чтобы сохранить преимущество, но только скрыть от пользователя вы можете удалить его программно. Кажется, что-то вроде хака, но рассмотреть вопрос о добавлении этого к вашему «OnCreate()» в вашем «» PreferenceActivity

getPreferenceScreen().removePreference(editTextPreferenceCharacterBlacklist); 

UPDATE

Похоже, ваша проблема вызвана editTextPreferenceCharacterBlacklist быть нулевым. Проблема, потому что она не была установлена ​​в вашу переменную экземпляра в той точке, в которой вы используете указанную строку. Вы можете попытаться найти его следующим образом:

getPreferenceScreen().removePreference(getPreferenceScreen().findPreference(KEY_CHARACTER_BLACKLIST));