A partir de 27 de março de 2025, recomendamos usar android-latest-release
em vez de aosp-main
para criar e contribuir com o AOSP. Para mais informações, consulte Mudanças no AOSP.
Preferências de legendas
Mantenha tudo organizado com as coleções
Salve e categorize o conteúdo com base nas suas preferências.
Na maioria das vezes, adicionar resumos de preferências é relativamente simples, porque
envolve apenas adicionar o atributo android:summary
à respectiva preferência
com o recurso de string adequado. No entanto, se as legendas precisarem ser atualizadas dinamicamente,
um controlador de preferências personalizado pode ser necessário.
Legendas estáticas
Para adicionar uma legenda estática a uma preferência:
- Adicione o atributo
android:summary
à preferência. Por exemplo, para adicionar um
resumo à preferência de configurações de exibição L0, adicione algo como o seguinte aos
atributos de preferência:
android:summary="@string/display_settings_summary"
Por exemplo, considere este exemplo de código de preferência 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"/>
Legendas dinâmicas
As legendas especificadas com o atributo android:summary
são estáticas e, portanto, não podem
ser atualizadas com base em determinadas condições. Para legendas dinâmicas, é necessário modificar o controlador
de preferência. O exemplo a seguir modifica a preferência de local L0 para
ter um subtítulo que especifica se a localização está ativada ou desativada e, se estiver ativada, informa quantos apps
têm acesso à localização.
- Defina as novas strings:
<!-- 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>
- Crie um novo PreferenceController,
LocationEntryPreferenceController
, para
definir e mudar dinamicamente o texto de resumo da preferência de local:
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 exemplo de controlador:
- Se o local estiver desativado, o texto do resumo será definido como a
string
location_settings_summary_location_off
.
- Se a localização estiver ativada, o número de apps que têm permissão de localização será adicionado. Enquanto
ele está sendo carregado, a string
location_settings_loading_app_permission_stats
é
mostrada. Quando os dados são carregados, o controlador define o resumo como a
string location_settings_summary_location_on
com o número de apps com
acesso especificado.
- Quando o controlador de preferência é iniciado, ele registra um receptor e
atualiza o estado da preferência quando o estado do local muda.
- Modifique o arquivo XML do fragmento para anexar o novo controlador à preferência 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"/>
O conteúdo e os exemplos de código nesta página estão sujeitos às licenças descritas na Licença de conteúdo. Java e OpenJDK são marcas registradas da Oracle e/ou suas afiliadas.
Última atualização 2025-07-27 UTC.
[[["Fácil de entender","easyToUnderstand","thumb-up"],["Meu problema foi resolvido","solvedMyProblem","thumb-up"],["Outro","otherUp","thumb-up"]],[["Não contém as informações de que eu preciso","missingTheInformationINeed","thumb-down"],["Muito complicado / etapas demais","tooComplicatedTooManySteps","thumb-down"],["Desatualizado","outOfDate","thumb-down"],["Problema na tradução","translationIssue","thumb-down"],["Problema com as amostras / o código","samplesCodeIssue","thumb-down"],["Outro","otherDown","thumb-down"]],["Última atualização 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 ```"]]