A partir del 27 de marzo de 2025, te recomendamos que uses android-latest-release
en lugar de aosp-main
para compilar y contribuir a AOSP. Para obtener más información, consulta Cambios en AOSP.
Subtítulos de preferencias
Organiza tus páginas con colecciones
Guarda y categoriza el contenido según tus preferencias.
En general, agregar resúmenes de preferencias es relativamente sencillo, ya que solo implica agregar el atributo android:summary
a la preferencia correspondiente con el recurso de cadena adecuado. Sin embargo, si los subtítulos deben actualizarse de forma dinámica, es posible que se necesite un controlador de preferencias personalizado.
Subtítulos estáticos
Para agregar un subtítulo estático a una preferencia, haz lo siguiente:
- Agrega el atributo
android:summary
a la preferencia. Por ejemplo, para agregar un resumen a la preferencia de configuración de la pantalla de L0, agrega algo como lo siguiente a los atributos de preferencia:
android:summary="@string/display_settings_summary"
Por ejemplo, considera este ejemplo de código de preferencia completo:
<Preference
android:fragment="com.android.car.settings.display.DisplaySettingsFragment"
android:icon="@drawable/ic_settings_display"
android:key="@string/pk_display_settings_entry"
android:title="@string/display_settings"
android:summary="@string/display_settings_summary"
settings:controller="com.android.car.settings.common.DefaultRestrictionsPreferenceController"/>
Subtítulos dinámicos
Los subtítulos especificados con el atributo android:summary
son estáticos, por lo que no se pueden actualizar en función de ciertas condiciones. Para los subtítulos dinámicos, debes modificar el controlador de preferencias de la preferencia. En el siguiente ejemplo, se modifica la preferencia de ubicación de L0 para que tenga un subtítulo que especifique si la ubicación está activada o desactivada y, si está activada, indique cuántas apps tienen acceso a la ubicación en ese momento.
- Define las cadenas nuevas:
<!-- Summary for Location settings when location is off [CHAR LIMIT=NONE] -->
<string name="location_settings_summary_location_off">Off</string>
<!-- Summary for Location settings when location is on, explaining how many apps have location permission [CHAR LIMIT=NONE]-->
<plurals name="location_settings_summary_location_on">
<item quantity="one">On - <xliff:g id="count">%1$d</xliff:g> app has access to location</item>
<item quantity="other">On - <xliff:g id="count">%1$d</xliff:g> apps have access to location</item>
</plurals>
<!-- Location settings, loading the number of apps which have location permission [CHAR LIMIT=30] -->
<string name="location_settings_loading_app_permission_stats">Loading\u2026</string>
- Crea un nuevo PreferenceController,
LocationEntryPreferenceController
, para establecer y cambiar de forma dinámica el texto de resumen de la preferencia de ubicación:
public class LocationEntryPreferenceController extends PreferenceController<Preference> {
private static final Logger LOG = new Logger(LocationEntryPreferenceController.class);
private static final IntentFilter INTENT_FILTER_LOCATION_MODE_CHANGED =
new IntentFilter(LocationManager.MODE_CHANGED_ACTION);
private final Context mContext;
private final LocationManager mLocationManager;
/** Total number of apps that have location permissions. */
private int mNumTotal = -1;
private int mNumTotalLoading = 0;
private AtomicInteger mLoadingInProgress = new AtomicInteger(0);
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
refreshUi();
}
};
public LocationEntryPreferenceController(Context context, String preferenceKey,
FragmentController fragmentController, CarUxRestrictions uxRestrictions) {
super(context, preferenceKey, fragmentController, uxRestrictions);
mContext = context;
mLocationManager = (LocationManager) getContext().getSystemService(
Service.LOCATION_SERVICE);
}
@Override
protected Class<Preference> getPreferenceType() {
return Preference.class;
}
@Override
protected void onStartInternal() {
getContext().registerReceiver(mReceiver, INTENT_FILTER_LOCATION_MODE_CHANGED);
}
@Override
protected void onStopInternal() {
getContext().unregisterReceiver(mReceiver);
}
@Override
protected void updateState(Preference preference) {
super.updateState(preference);
updateSummary(preference);
if (!mLocationManager.isLocationEnabled() || mLoadingInProgress.get() != 0) {
return;
}
mNumTotalLoading = 0;
// Retrieve a list of users inside the current user profile group.
List<UserHandle> users = mContext.getSystemService(
UserManager.class).getUserProfiles();
mLoadingInProgress.set(users.size());
for (UserHandle user : users) {
Context userContext = createPackageContextAsUser(mContext, user.getIdentifier());
if (userContext == null) {
if (mLoadingInProgress.decrementAndGet() == 0) {
setLocationAppCount(preference, mNumTotalLoading);
}
continue;
}
PermissionControllerManager permController =
userContext.getSystemService(PermissionControllerManager.class);
permController.countPermissionApps(
Arrays.asList(ACCESS_FINE_LOCATION, ACCESS_COARSE_LOCATION),
PermissionControllerManager.COUNT_ONLY_WHEN_GRANTED,
(numApps) -> {
mNumTotalLoading += numApps;
if (mLoadingInProgress.decrementAndGet() == 0) {
setLocationAppCount(preference, mNumTotalLoading);
}
}, null);
}
}
@VisibleForTesting
void setLocationAppCount(Preference preference, int numApps) {
mNumTotal = numApps;
updateSummary(preference);
}
private void updateSummary(Preference preference) {
String summary = "";
if (mLocationManager.isLocationEnabled()) {
if (mNumTotal == -1) {
summary = mContext.getString(R.string.location_settings_loading_app_permission_stats);
} else {
summary = mContext.getResources().getQuantityString(
R.plurals.location_settings_summary_location_on,
mNumTotal, mNumTotal);
}
} else {
summary = mContext.getString(R.string.location_settings_summary_location_off);
}
preference.setSummary(summary);
}
private Context createPackageContextAsUser(Context context, int userId) {
try {
return context.createPackageContextAsUser(
context.getPackageName(), 0 /* flags */, UserHandle.of(userId));
} catch (PackageManager.NameNotFoundException e) {
LOG.e("Failed to create user context", e);
}
return null;
}
}
Para este controlador de ejemplo:
- Si la ubicación está inhabilitada, el texto del resumen se establece en la cadena
location_settings_summary_location_off
.
- Si la ubicación está habilitada, se agrega la cantidad de apps que tienen permiso de ubicación. Mientras se carga, se muestra la cadena
location_settings_loading_app_permission_stats
. Cuando se cargan los datos, el controlador establece el resumen en la cadena location_settings_summary_location_on
con la cantidad de apps con acceso especificado.
- Cuando se inicia el controlador de preferencias, este registra un receptor y actualiza el estado de la preferencia cuando cambia el estado de la ubicación.
- Modifica el archivo en formato XML del fragmento para conectar el nuevo controlador a la preferencia relevante:
<Preference
android:fragment="com.android.car.settings.location.LocationSettingsFragment"
android:icon="@drawable/ic_settings_location"
android:key="@string/pk_location_settings_entry"
android:title="@string/location_settings_title"
settings:controller="com.android.car.settings.location.LocationEntryPreferenceController"/>
El contenido y las muestras de código que aparecen en esta página están sujetas a las licencias que se describen en la Licencia de Contenido. Java y OpenJDK son marcas registradas de Oracle o sus afiliados.
Última actualización: 2025-07-27 (UTC)
[[["Fácil de comprender","easyToUnderstand","thumb-up"],["Resolvió mi problema","solvedMyProblem","thumb-up"],["Otro","otherUp","thumb-up"]],[["Falta la información que necesito","missingTheInformationINeed","thumb-down"],["Muy complicado o demasiados pasos","tooComplicatedTooManySteps","thumb-down"],["Desactualizado","outOfDate","thumb-down"],["Problema de traducción","translationIssue","thumb-down"],["Problema con las muestras o los códigos","samplesCodeIssue","thumb-down"],["Otro","otherDown","thumb-down"]],["Última actualización: 2025-07-27 (UTC)"],[],[],null,["# Preference subtitles\n\nFor the most part, adding preference summaries is relatively straightforward as it\ninvolves just adding the `android:summary` attribute to the respective preference\nwith the appropriate string resource. However, if the subtitles should update dynamically\nthen a custom preference controller may be necessary.\n\nStatic subtitles\n----------------\n\nTo add a static subtitle to a preference:\n\n1. Add the `android:summary` attribute to the preference. For example, to add a summary to the L0 display settings preference, add something like the following to the preference attributes: \n\n android:summary=\"@string/display_settings_summary\"\n\n For example, consider this full preference code sample: \n\n ```\n \u003cPreference\n android:fragment=\"com.android.car.settings.display.DisplaySettingsFragment\"\n android:icon=\"@drawable/ic_settings_display\"\n android:key=\"@string/pk_display_settings_entry\"\n android:title=\"@string/display_settings\"\n android:summary=\"@string/display_settings_summary\"\n settings:controller=\"com.android.car.settings.common.DefaultRestrictionsPreferenceController\"/\u003e\n ```\n\nDynamic subtitles\n-----------------\n\nSubtitles specified with the `android:summary` attribute are static so cannot\nupdate based on certain conditions. For dynamic subtitles, you need to modify the preference\ncontroller for the preference. The following example modifies the L0 location preference to\nhave a subtitle that specifies if location is on or off and, if on, state how many apps\ncurrently have location access.\n\n1. Define the new strings: \n\n ```\n \u003c!-- Summary for Location settings when location is off [CHAR LIMIT=NONE] --\u003e\n \u003cstring name=\"location_settings_summary_location_off\"\u003eOff\u003c/string\u003e\n \u003c!-- Summary for Location settings when location is on, explaining how many apps have location permission [CHAR LIMIT=NONE]--\u003e\n \u003cplurals name=\"location_settings_summary_location_on\"\u003e\n \u003citem quantity=\"one\"\u003eOn - \u003cxliff:g id=\"count\"\u003e%1$d\u003c/xliff:g\u003e app has access to location\u003c/item\u003e\n \u003citem quantity=\"other\"\u003eOn - \u003cxliff:g id=\"count\"\u003e%1$d\u003c/xliff:g\u003e apps have access to location\u003c/item\u003e\n \u003c/plurals\u003e\n \u003c!-- Location settings, loading the number of apps which have location permission [CHAR LIMIT=30] --\u003e\n \u003cstring name=\"location_settings_loading_app_permission_stats\"\u003eLoading\\u2026\u003c/string\u003e\n ```\n2. Create a new PreferenceController, `LocationEntryPreferenceController`, to dynamically set and change the location preference summary text: \n\n ```\n public class LocationEntryPreferenceController extends PreferenceController\u003cPreference\u003e {\n\n private static final Logger LOG = new Logger(LocationEntryPreferenceController.class);\n private static final IntentFilter INTENT_FILTER_LOCATION_MODE_CHANGED =\n new IntentFilter(LocationManager.MODE_CHANGED_ACTION);\n\n private final Context mContext;\n private final LocationManager mLocationManager;\n /** Total number of apps that have location permissions. */\n private int mNumTotal = -1;\n private int mNumTotalLoading = 0;\n private AtomicInteger mLoadingInProgress = new AtomicInteger(0);\n\n private final BroadcastReceiver mReceiver = new BroadcastReceiver() {\n @Override\n public void onReceive(Context context, Intent intent) {\n refreshUi();\n }\n };\n\n public LocationEntryPreferenceController(Context context, String preferenceKey,\n FragmentController fragmentController, CarUxRestrictions uxRestrictions) {\n super(context, preferenceKey, fragmentController, uxRestrictions);\n mContext = context;\n mLocationManager = (LocationManager) getContext().getSystemService(\n Service.LOCATION_SERVICE);\n }\n\n @Override\n protected Class\u003cPreference\u003e getPreferenceType() {\n return Preference.class;\n }\n\n @Override\n protected void onStartInternal() {\n getContext().registerReceiver(mReceiver, INTENT_FILTER_LOCATION_MODE_CHANGED);\n }\n\n @Override\n protected void onStopInternal() {\n getContext().unregisterReceiver(mReceiver);\n }\n\n @Override\n protected void updateState(Preference preference) {\n super.updateState(preference);\n updateSummary(preference);\n if (!mLocationManager.isLocationEnabled() || mLoadingInProgress.get() != 0) {\n return;\n }\n mNumTotalLoading = 0;\n // Retrieve a list of users inside the current user profile group.\n List\u003cUserHandle\u003e users = mContext.getSystemService(\n UserManager.class).getUserProfiles();\n mLoadingInProgress.set(users.size());\n for (UserHandle user : users) {\n Context userContext = createPackageContextAsUser(mContext, user.getIdentifier());\n if (userContext == null) {\n if (mLoadingInProgress.decrementAndGet() == 0) {\n setLocationAppCount(preference, mNumTotalLoading);\n }\n continue;\n }\n PermissionControllerManager permController =\n userContext.getSystemService(PermissionControllerManager.class);\n permController.countPermissionApps(\n Arrays.asList(ACCESS_FINE_LOCATION, ACCESS_COARSE_LOCATION),\n PermissionControllerManager.COUNT_ONLY_WHEN_GRANTED,\n (numApps) -\u003e {\n mNumTotalLoading += numApps;\n if (mLoadingInProgress.decrementAndGet() == 0) {\n setLocationAppCount(preference, mNumTotalLoading);\n }\n }, null);\n }\n }\n\n @VisibleForTesting\n void setLocationAppCount(Preference preference, int numApps) {\n mNumTotal = numApps;\n updateSummary(preference);\n }\n\n private void updateSummary(Preference preference) {\n String summary = \"\";\n if (mLocationManager.isLocationEnabled()) {\n if (mNumTotal == -1) {\n summary = mContext.getString(R.string.location_settings_loading_app_permission_stats);\n } else {\n summary = mContext.getResources().getQuantityString(\n R.plurals.location_settings_summary_location_on,\n mNumTotal, mNumTotal);\n }\n } else {\n summary = mContext.getString(R.string.location_settings_summary_location_off);\n }\n preference.setSummary(summary);\n }\n\n private Context createPackageContextAsUser(Context context, int userId) {\n try {\n return context.createPackageContextAsUser(\n context.getPackageName(), 0 /* flags */, UserHandle.of(userId));\n } catch (PackageManager.NameNotFoundException e) {\n LOG.e(\"Failed to create user context\", e);\n }\n return null;\n }\n }\n ```\n\n For this sample controller:\n - If location is disabled, summary text is set to the `location_settings_summary_location_off` string.\n - If location is enabled, the number of apps that have location permission is added. While this is loading, the `location_settings_loading_app_permission_stats` string is shown. When the data is loaded, the controller sets the summary to the `location_settings_summary_location_on` string with the number of apps with access specified.\n - When the preference controller is started, the controller registers a receiver and refreshes the preference state when the location state changes.\n3. Modify the fragment XML file to attach the new controller to the relevant preference: \n\n ```\n \u003cPreference\n android:fragment=\"com.android.car.settings.location.LocationSettingsFragment\"\n android:icon=\"@drawable/ic_settings_location\"\n android:key=\"@string/pk_location_settings_entry\"\n android:title=\"@string/location_settings_title\"\n settings:controller=\"com.android.car.settings.location.LocationEntryPreferenceController\"/\u003e\n ```"]]