Module java.base
Package java.util

Class ResourceBundle

  • Direct Known Subclasses:
    ListResourceBundle,PropertyResourceBundle
    public abstract classResourceBundleextendsObject
    Resource bundles contain locale-specific objects. When your program needs a locale-specific resource, aString for example, your program can load it from the resource bundle that is appropriate for the current user's locale. In this way, you can write program code that is largely independent of the user's locale isolating most, if not all, of the locale-specific information in resource bundles.

    This allows you to write programs that can:

    • be easily localized, or translated, into different languages
    • handle multiple locales at once
    • be easily modified later to support even more locales

    Resource bundles belong to families whose members share a common base name, but whose names also have additional components that identify their locales. For example, the base name of a family of resource bundles might be "MyResources". The family should have a default resource bundle which simply has the same name as its family - "MyResources" - and will be used as the bundle of last resort if a specific locale is not supported. The family can then provide as many locale-specific members as needed, for example a German one named "MyResources_de".

    Each resource bundle in a family contains the same items, but the items have been translated for the locale represented by that resource bundle. For example, both "MyResources" and "MyResources_de" may have aString that's used on a button for canceling operations. In "MyResources" theString may contain "Cancel" and in "MyResources_de" it may contain "Abbrechen".

    If there are different resources for different countries, you can make specializations: for example, "MyResources_de_CH" contains objects for the German language (de) in Switzerland (CH). If you want to only modify some of the resources in the specialization, you can do so.

    When your program needs a locale-specific object, it loads theResourceBundle class using thegetBundle method:

     ResourceBundle myResources =      ResourceBundle.getBundle("MyResources", currentLocale);

    Resource bundles contain key/value pairs. The keys uniquely identify a locale-specific object in the bundle. Here's an example of aListResourceBundle that contains two key/value pairs:

     public class MyResources extends ListResourceBundle {     protected Object[][] getContents() {         return new Object[][] {             // LOCALIZE THE SECOND STRING OF EACH ARRAY (e.g., "OK")             {"OkKey", "OK"},             {"CancelKey", "Cancel"},             // END OF MATERIAL TO LOCALIZE        };     } }
    Keys are alwaysStrings. In this example, the keys are "OkKey" and "CancelKey". In the above example, the values are alsoStrings--"OK" and "Cancel"--but they don't have to be. The values can be any type of object.

    You retrieve an object from resource bundle using the appropriate getter method. Because "OkKey" and "CancelKey" are both strings, you would usegetString to retrieve them:

     button1 = new Button(myResources.getString("OkKey")); button2 = new Button(myResources.getString("CancelKey"));
    The getter methods all require the key as an argument and return the object if found. If the object is not found, the getter method throws aMissingResourceException.

    BesidesgetString,ResourceBundle also provides a method for getting string arrays,getStringArray, as well as a genericgetObject method for any other type of object. When usinggetObject, you'll have to cast the result to the appropriate type. For example:

     int[] myIntegers = (int[]) myResources.getObject("intList");

    The Java Platform provides two subclasses ofResourceBundle,ListResourceBundle andPropertyResourceBundle, that provide a fairly simple way to create resources. As you saw briefly in a previous example,ListResourceBundle manages its resource as a list of key/value pairs.PropertyResourceBundle uses a properties file to manage its resources.

    IfListResourceBundle orPropertyResourceBundle do not suit your needs, you can write your ownResourceBundle subclass. Your subclasses must override two methods:handleGetObject andgetKeys().

    The implementation of aResourceBundle subclass must be thread-safe if it's simultaneously used by multiple threads. The default implementations of the non-abstract methods in this class, and the methods in the direct known concrete subclassesListResourceBundle andPropertyResourceBundle are thread-safe.

    Resource Bundles and Named Modules

    Resource bundles can be deployed in modules in the following ways:

    Resource bundles together with an application

    Resource bundles can be deployed together with an application in the same module. In that case, the resource bundles are loaded by code in the module by calling thegetBundle(String) orgetBundle(String, Locale) method.

    Resource bundles as service providers

    Resource bundles can be deployed in one or moreservice provider modules and they can be located usingServiceLoader. Aservice interface or class must be defined. The caller module declares that it uses the service, the service provider modules declare that they provide implementations of the service. Refer toResourceBundleProvider for developing resource bundle services and deploying resource bundle providers. The module obtaining the resource bundle can be a resource bundle provider itself; in which case this module only locates the resource bundle via service provider mechanism.

    Aresource bundle provider can provide resource bundles in any format such XML which replaces the need ofResourceBundle.Control.

    Resource bundles in other modules and class path

    Resource bundles in a named module may beencapsulated so that it cannot be located by code in other modules. Resource bundles in unnamed modules and class path are open for any module to access. Resource bundle follows the resource encapsulation rules as specified inModule.getResourceAsStream(String).

    ThegetBundle factory methods with noControl parameter locate and load resource bundles fromservice providers. It may continue the search as if callingModule.getResourceAsStream(String) to find the named resource from a given module and callingClassLoader.getResourceAsStream(String); refer to the specification of thegetBundle method for details. Only non-encapsulated resource bundles of "java.class" or "java.properties" format are searched.

    If the caller module is a resource bundle provider, it does not fall back to the class loader search.

    Resource bundles in automatic modules

    A common format of resource bundles is in.properties file format. Typically.properties resource bundles are packaged in a JAR file. Resource bundle only JAR file can be readily deployed as an automatic module. For example, if the JAR file contains the entry "p/q/Foo_ja.properties" and no.class entry, when resolved and defined as an automatic module, no package is derived for this module. This allows resource bundles in.properties format packaged in one or more JAR files that may contain entries in the same directory and can be resolved successfully as automatic modules.

    ResourceBundle.Control

    TheResourceBundle.Control class provides information necessary to perform the bundle loading process by thegetBundle factory methods that take aResourceBundle.Control instance. You can implement your own subclass in order to enable non-standard resource bundle formats, change the search strategy, or define caching parameters. Refer to the descriptions of the class and thegetBundle factory method for details.

    ResourceBundle.Control is designed for an application deployed in an unnamed module, for example to support resource bundles in non-standard formats or package localized resources in a non-traditional convention.ResourceBundleProvider is the replacement forResourceBundle.Control when migrating to modules.UnsupportedOperationException will be thrown when a factory method that takes theResourceBundle.Control parameter is called.

    For thegetBundle factory methods that take noResourceBundle.Control instance, their default behavior of resource bundle loading can be modified with customResourceBundleControlProvider implementations. If any of the providers provides aResourceBundle.Control for the given base name, thatResourceBundle.Control will be used instead of the defaultResourceBundle.Control. If there is more than one service provider for supporting the same base name, the first one returned fromServiceLoader will be used. A customResourceBundle.Control implementation is ignored by named modules.

    Cache Management

    Resource bundle instances created by thegetBundle factory methods are cached by default, and the factory methods return the same resource bundle instance multiple times if it has been cached.getBundle clients may clear the cache, manage the lifetime of cached resource bundle instances using time-to-live values, or specify not to cache resource bundle instances. Refer to the descriptions of thegetBundlefactory method,clearCache,ResourceBundle.Control.getTimeToLive, andResourceBundle.Control.needsReload for details.

    Example

    The following is a very simple example of aResourceBundle subclass,MyResources, that manages two resources (for a larger number of resources you would probably use aMap). Notice that you don't need to supply a value if a "parent-level"ResourceBundle handles the same key with the same value (as for the okKey below).
     // default (English language, United States) public class MyResources extends ResourceBundle {     public Object handleGetObject(String key) {         if (key.equals("okKey")) return "Ok";         if (key.equals("cancelKey")) return "Cancel";         return null;     }     public Enumeration<String> getKeys() {         return Collections.enumeration(keySet());     }     // Overrides handleKeySet() so that the getKeys() implementation     // can rely on the keySet() value.     protected Set<String> handleKeySet() {         return new HashSet<String>(Arrays.asList("okKey", "cancelKey"));     } } // German language public class MyResources_de extends MyResources {     public Object handleGetObject(String key) {         // don't need okKey, since parent level handles it.         if (key.equals("cancelKey")) return "Abbrechen";         return null;     }     protected Set<String> handleKeySet() {         return new HashSet<String>(Arrays.asList("cancelKey"));     } }
    You do not have to restrict yourself to using a single family ofResourceBundles. For example, you could have a set of bundles for exception messages,ExceptionResources (ExceptionResources_fr,ExceptionResources_de, ...), and one for widgets,WidgetResource (WidgetResources_fr,WidgetResources_de, ...); breaking up the resources however you like.
    Since:
    1.1
    See Also:
    ListResourceBundle,PropertyResourceBundle,MissingResourceException,ResourceBundleProvider

    • Field Detail

      • parent

        protected ResourceBundle parent
        The parent bundle of this bundle. The parent bundle is searched bygetObject when this bundle does not contain a particular resource.

    • Constructor Detail

      • ResourceBundle

        public ResourceBundle()
        Sole constructor. (For invocation by subclass constructors, typically implicit.)

    • Method Detail

      • getBaseBundleName

        public String getBaseBundleName()
        Returns the base name of this bundle, if known, ornull if unknown. If not null, then this is the value of thebaseName parameter that was passed to theResourceBundle.getBundle(...) method when the resource bundle was loaded.
        Returns:
        The base name of the resource bundle, as provided to and expected by theResourceBundle.getBundle(...) methods.
        Since:
        1.8
        See Also:
        getBundle(java.lang.String, java.util.Locale, java.lang.ClassLoader)

      • getString

        public final String getString​(String key)
        Gets a string for the given key from this resource bundle or one of its parents. Calling this method is equivalent to calling
        (String)getObject(key).
        Parameters:
        key - the key for the desired string
        Returns:
        the string for the given key
        Throws:
        NullPointerException - ifkey isnull
        MissingResourceException - if no object for the given key can be found
        ClassCastException - if the object found for the given key is not a string

      • getStringArray

        public final String[] getStringArray​(String key)
        Gets a string array for the given key from this resource bundle or one of its parents. Calling this method is equivalent to calling
        (String[])getObject(key).
        Parameters:
        key - the key for the desired string array
        Returns:
        the string array for the given key
        Throws:
        NullPointerException - ifkey isnull
        MissingResourceException - if no object for the given key can be found
        ClassCastException - if the object found for the given key is not a string array

      • getObject

        public final Object getObject​(String key)
        Gets an object for the given key from this resource bundle or one of its parents. This method first tries to obtain the object from this resource bundle usinghandleGetObject. If not successful, and the parent resource bundle is not null, it calls the parent'sgetObject method. If still not successful, it throws a MissingResourceException.
        Parameters:
        key - the key for the desired object
        Returns:
        the object for the given key
        Throws:
        NullPointerException - ifkey isnull
        MissingResourceException - if no object for the given key can be found

      • getLocale

        public Locale getLocale()
        Returns the locale of this resource bundle. This method can be used after a call to getBundle() to determine whether the resource bundle returned really corresponds to the requested locale or is a fallback.
        Returns:
        the locale of this resource bundle

      • setParent

        protected void setParent​(ResourceBundle parent)
        Sets the parent bundle of this bundle. The parent bundle is searched bygetObject when this bundle does not contain a particular resource.
        Parameters:
        parent - this bundle's parent bundle.

      • getBundle

        public static final ResourceBundle getBundle​(String baseName,ResourceBundle.Control control)
        Returns a resource bundle using the specified base name, the default locale and the specified control. Calling this method is equivalent to calling
         getBundle(baseName, Locale.getDefault(),           this.getClass().getClassLoader(), control),
        except thatgetClassLoader() is run with the security privileges ofResourceBundle. SeegetBundle for the complete description of the resource bundle loading process with aResourceBundle.Control.
        Parameters:
        baseName - the base name of the resource bundle, a fully qualified class name
        control - the control which gives information for the resource bundle loading process
        Returns:
        a resource bundle for the given base name and the default locale
        Throws:
        NullPointerException - ifbaseName orcontrol isnull
        MissingResourceException - if no resource bundle for the specified base name can be found
        IllegalArgumentException - if the givencontrol doesn't perform properly (e.g.,control.getCandidateLocales returns null.) Note that validation ofcontrol is performed as needed.
        UnsupportedOperationException - if this method is called in a named module
        Since:
        1.6

      • getBundle

        public static ResourceBundle getBundle​(String baseName,Module module)
        Gets a resource bundle using the specified base name and the default locale on behalf of the specified module. This method is equivalent to calling
        getBundle(baseName, Locale.getDefault(), module)
        Parameters:
        baseName - the base name of the resource bundle, a fully qualified class name
        module - the module for which the resource bundle is searched
        Returns:
        a resource bundle for the given base name and the default locale
        Throws:
        NullPointerException - ifbaseName ormodule isnull
        SecurityException - if a security manager exists and the caller is not the specified module and doesn't haveRuntimePermission("getClassLoader")
        MissingResourceException - if no resource bundle for the specified base name can be found in the specified module
        Since:
        9
        See Also:
        ResourceBundleProvider,Resource Bundle Search and Loading Strategy,Resource Bundles and Named Modules

      • getBundle

        public static final ResourceBundle getBundle​(String baseName,Locale targetLocale,ResourceBundle.Control control)
        Returns a resource bundle using the specified base name, target locale and control, and the caller's class loader. Calling this method is equivalent to calling
         getBundle(baseName, targetLocale, this.getClass().getClassLoader(),           control),
        except thatgetClassLoader() is run with the security privileges ofResourceBundle. SeegetBundle for the complete description of the resource bundle loading process with aResourceBundle.Control.
        Parameters:
        baseName - the base name of the resource bundle, a fully qualified class name
        targetLocale - the locale for which a resource bundle is desired
        control - the control which gives information for the resource bundle loading process
        Returns:
        a resource bundle for the given base name and aLocale inlocales
        Throws:
        NullPointerException - ifbaseName,locales orcontrol isnull
        MissingResourceException - if no resource bundle for the specified base name in any of thelocales can be found.
        IllegalArgumentException - if the givencontrol doesn't perform properly (e.g.,control.getCandidateLocales returns null.) Note that validation ofcontrol is performed as needed.
        UnsupportedOperationException - if this method is called in a named module
        Since:
        1.6

      • getBundle

        public static ResourceBundle getBundle​(String baseName,Locale locale,ClassLoader loader)
        Gets a resource bundle using the specified base name, locale, and class loader.

        When this method is called from a named module and the given loader is the class loader of the caller module, this is equivalent to calling:

         getBundle(baseName, targetLocale, callerModule)
        otherwise, this is equivalent to calling:
         getBundle(baseName, targetLocale, loader, control)
        wherecontrol is the default instance ofResourceBundle.Control unless aControl instance is provided byResourceBundleControlProvider SPI. Refer to the description ofmodifying the default behavior. The following describes the default behavior.

        Resource Bundle Search and Loading Strategy

        getBundle uses the base name, the specified locale, and the default locale (obtained fromLocale.getDefault) to generate a sequence ofcandidate bundle names. If the specified locale's language, script, country, and variant are all empty strings, then the base name is the only candidate bundle name. Otherwise, a list of candidate locales is generated from the attribute values of the specified locale (language, script, country and variant) and appended to the base name. Typically, this will look like the following:

             baseName + "_" + language + "_" + script + "_" + country + "_" + variant     baseName + "_" + language + "_" + script + "_" + country     baseName + "_" + language + "_" + script     baseName + "_" + language + "_" + country + "_" + variant     baseName + "_" + language + "_" + country     baseName + "_" + language

        Candidate bundle names where the final component is an empty string are omitted, along with the underscore. For example, if country is an empty string, the second and the fifth candidate bundle names above would be omitted. Also, if script is an empty string, the candidate names including script are omitted. For example, a locale with language "de" and variant "JAVA" will produce candidate names with base name "MyResource" below.

             MyResource_de__JAVA     MyResource_de
        In the case that the variant contains one or more underscores ('_'), a sequence of bundle names generated by truncating the last underscore and the part following it is inserted after a candidate bundle name with the original variant. For example, for a locale with language "en", script "Latn, country "US" and variant "WINDOWS_VISTA", and bundle base name "MyResource", the list of candidate bundle names below is generated:
         MyResource_en_Latn_US_WINDOWS_VISTA MyResource_en_Latn_US_WINDOWS MyResource_en_Latn_US MyResource_en_Latn MyResource_en_US_WINDOWS_VISTA MyResource_en_US_WINDOWS MyResource_en_US MyResource_en
        Note: For someLocales, the list of candidate bundle names contains extra names, or the order of bundle names is slightly modified. See the description of the default implementation ofgetCandidateLocales for details.

        getBundle then iterates over the candidate bundle names to find the first one for which it caninstantiate an actual resource bundle. It uses the default controls'getFormats method, which generates two bundle names for each generated name, the first a class name and the second a properties file name. For each candidate bundle name, it attempts to create a resource bundle:

        • First, it attempts to load a class using the generated class name. If such a class can be found and loaded using the specified class loader, is assignment compatible with ResourceBundle, is accessible from ResourceBundle, and can be instantiated,getBundle creates a new instance of this class and uses it as theresult resource bundle.
        • Otherwise,getBundle attempts to locate a property resource file using the generated properties file name. It generates a path name from the candidate bundle name by replacing all "." characters with "/" and appending the string ".properties". It attempts to find a "resource" with this name usingClassLoader.getResource. (Note that a "resource" in the sense ofgetResource has nothing to do with the contents of a resource bundle, it is just a container of data, such as a file.) If it finds a "resource", it attempts to create a newPropertyResourceBundle instance from its contents. If successful, this instance becomes theresult resource bundle.

        This continues until a result resource bundle is instantiated or the list of candidate bundle names is exhausted. If no matching resource bundle is found, the default control'sgetFallbackLocale method is called, which returns the current default locale. A new sequence of candidate locale names is generated using this locale and searched again, as above.

        If still no result bundle is found, the base name alone is looked up. If this still fails, aMissingResourceException is thrown.

        Once a result resource bundle has been found, itsparent chain is instantiated. If the result bundle already has a parent (perhaps because it was returned from a cache) the chain is complete.

        Otherwise,getBundle examines the remainder of the candidate locale list that was used during the pass that generated the result resource bundle. (As before, candidate bundle names where the final component is an empty string are omitted.) When it comes to the end of the candidate list, it tries the plain bundle name. With each of the candidate bundle names it attempts to instantiate a resource bundle (first looking for a class and then a properties file, as described above).

        Whenever it succeeds, it calls the previously instantiated resource bundle'ssetParent method with the new resource bundle. This continues until the list of names is exhausted or the current bundle already has a non-null parent.

        Once the parent chain is complete, the bundle is returned.

        Note:getBundle caches instantiated resource bundles and might return the same resource bundle instance multiple times.

        Note:ThebaseName argument should be a fully qualified class name. However, for compatibility with earlier versions, Java SE Runtime Environments do not verify this, and so it is possible to accessPropertyResourceBundles by specifying a path name (using "/") instead of a fully qualified class name (using ".").

        Example:

        The following class and property files are provided:

        • MyResources.class
        • MyResources.properties
        • MyResources_fr.properties
        • MyResources_fr_CH.class
        • MyResources_fr_CH.properties
        • MyResources_en.properties
        • MyResources_es_ES.class
        The contents of all files are valid (that is, public non-abstract subclasses ofResourceBundle for the ".class" files, syntactically correct ".properties" files). The default locale isLocale("en", "GB").

        CallinggetBundle with the locale arguments below will instantiate resource bundles as follows:

        getBundle() locale to resource bundle mapping
        LocaleResource bundle
        Locale("fr", "CH")MyResources_fr_CH.class, parent MyResources_fr.properties, parent MyResources.class
        Locale("fr", "FR")MyResources_fr.properties, parent MyResources.class
        Locale("de", "DE")MyResources_en.properties, parent MyResources.class
        Locale("en", "US")MyResources_en.properties, parent MyResources.class
        Locale("es", "ES")MyResources_es_ES.class, parent MyResources.class

        The file MyResources_fr_CH.properties is never used because it is hidden by the MyResources_fr_CH.class. Likewise, MyResources.properties is also hidden by MyResources.class.

        API Note:
        If the caller module is a named module and the givenloader is the caller module's class loader, this method is equivalent togetBundle(baseName, locale); otherwise, it may not find resource bundles from named modules. UsegetBundle(String, Locale, Module) to load resource bundles on behalf on a specific module instead.
        Parameters:
        baseName - the base name of the resource bundle, a fully qualified class name
        locale - the locale for which a resource bundle is desired
        loader - the class loader from which to load the resource bundle
        Returns:
        a resource bundle for the given base name and locale
        Throws:
        NullPointerException - ifbaseName,locale, orloader isnull
        MissingResourceException - if no resource bundle for the specified base name can be found
        Since:
        1.2
        See Also:
        Resource Bundles and Named Modules

      • getBundle

        public static ResourceBundle getBundle​(String baseName,Locale targetLocale,ClassLoader loader,ResourceBundle.Control control)
        Returns a resource bundle using the specified base name, target locale, class loader and control. Unlike thegetBundle factory methods with nocontrol argument, the givencontrol specifies how to locate and instantiate resource bundles. Conceptually, the bundle loading process with the givencontrol is performed in the following steps.
        1. This factory method looks up the resource bundle in the cache for the specifiedbaseName,targetLocale andloader. If the requested resource bundle instance is found in the cache and the time-to-live periods of the instance and all of its parent instances have not expired, the instance is returned to the caller. Otherwise, this factory method proceeds with the loading process below.
        2. Thecontrol.getFormats method is called to get resource bundle formats to produce bundle or resource names. The strings"java.class" and"java.properties" designate class-based andproperty-based resource bundles, respectively. Other strings starting with"java." are reserved for future extensions and must not be used for application-defined formats. Other strings designate application-defined formats.
        3. Thecontrol.getCandidateLocales method is called with the target locale to get a list ofcandidateLocales for which resource bundles are searched.
        4. Thecontrol.newBundle method is called to instantiate aResourceBundle for the base bundle name, a candidate locale, and a format. (Refer to the note on the cache lookup below.) This step is iterated over all combinations of the candidate locales and formats until thenewBundle method returns aResourceBundle instance or the iteration has used up all the combinations. For example, if the candidate locales areLocale("de", "DE"),Locale("de") andLocale("") and the formats are"java.class" and"java.properties", then the following is the sequence of locale-format combinations to be used to callcontrol.newBundle.
          locale-format combinations for newBundle
          IndexLocaleformat
          1Locale("de", "DE")java.class
          2Locale("de", "DE")java.properties
          3Locale("de")java.class
          4Locale("de")java.properties
          5Locale("")java.class
          6Locale("")java.properties
        5. If the previous step has found no resource bundle, proceed to Step 6. If a bundle has been found that is a base bundle (a bundle forLocale("")), and the candidate locale list only containedLocale(""), return the bundle to the caller. If a bundle has been found that is a base bundle, but the candidate locale list contained locales other than Locale(""), put the bundle on hold and proceed to Step 6. If a bundle has been found that is not a base bundle, proceed to Step 7.
        6. Thecontrol.getFallbackLocale method is called to get a fallback locale (alternative to the current target locale) to try further finding a resource bundle. If the method returns a non-null locale, it becomes the next target locale and the loading process starts over from Step 3. Otherwise, if a base bundle was found and put on hold in a previous Step 5, it is returned to the caller now. Otherwise, a MissingResourceException is thrown.
        7. At this point, we have found a resource bundle that's not the base bundle. If this bundle set its parent during its instantiation, it is returned to the caller. Otherwise, itsparent chain is instantiated based on the list of candidate locales from which it was found. Finally, the bundle is returned to the caller.

        During the resource bundle loading process above, this factory method looks up the cache before calling thecontrol.newBundle method. If the time-to-live period of the resource bundle found in the cache has expired, the factory method calls thecontrol.needsReload method to determine whether the resource bundle needs to be reloaded. If reloading is required, the factory method callscontrol.newBundle to reload the resource bundle. Ifcontrol.newBundle returnsnull, the factory method puts a dummy resource bundle in the cache as a mark of nonexistent resource bundles in order to avoid lookup overhead for subsequent requests. Such dummy resource bundles are under the same expiration control as specified bycontrol.

        All resource bundles loaded are cached by default. Refer tocontrol.getTimeToLive for details.

        The following is an example of the bundle loading process with the defaultResourceBundle.Control implementation.

        Conditions:

        • Base bundle name:foo.bar.Messages
        • RequestedLocale:Locale.ITALY
        • DefaultLocale:Locale.FRENCH
        • Available resource bundles:foo/bar/Messages_fr.properties andfoo/bar/Messages.properties

        First,getBundle tries loading a resource bundle in the following sequence.

        • classfoo.bar.Messages_it_IT
        • filefoo/bar/Messages_it_IT.properties
        • classfoo.bar.Messages_it
        • filefoo/bar/Messages_it.properties
        • classfoo.bar.Messages
        • filefoo/bar/Messages.properties

        At this point,getBundle findsfoo/bar/Messages.properties, which is put on hold because it's the base bundle.getBundle callscontrol.getFallbackLocale("foo.bar.Messages", Locale.ITALY) which returnsLocale.FRENCH. Next,getBundle tries loading a bundle in the following sequence.

        • classfoo.bar.Messages_fr
        • filefoo/bar/Messages_fr.properties
        • classfoo.bar.Messages
        • filefoo/bar/Messages.properties

        getBundle findsfoo/bar/Messages_fr.properties and creates aResourceBundle instance. Then,getBundle sets up its parent chain from the list of the candidate locales. Onlyfoo/bar/Messages.properties is found in the list andgetBundle creates aResourceBundle instance that becomes the parent of the instance forfoo/bar/Messages_fr.properties.

        Parameters:
        baseName - the base name of the resource bundle, a fully qualified class name
        targetLocale - the locale for which a resource bundle is desired
        loader - the class loader from which to load the resource bundle
        control - the control which gives information for the resource bundle loading process
        Returns:
        a resource bundle for the given base name and locale
        Throws:
        NullPointerException - ifbaseName,targetLocale,loader, orcontrol isnull
        MissingResourceException - if no resource bundle for the specified base name can be found
        IllegalArgumentException - if the givencontrol doesn't perform properly (e.g.,control.getCandidateLocales returns null.) Note that validation ofcontrol is performed as needed.
        UnsupportedOperationException - if this method is called in a named module
        Since:
        1.6

      • handleGetObject

        protected abstract Object handleGetObject​(String key)
        Gets an object for the given key from this resource bundle. Returns null if this resource bundle does not contain an object for the given key.
        Parameters:
        key - the key for the desired object
        Returns:
        the object for the given key, or null
        Throws:
        NullPointerException - ifkey isnull

      • getKeys

        public abstract Enumeration<String> getKeys()
        Returns an enumeration of the keys.
        Returns:
        anEnumeration of the keys contained in thisResourceBundle and its parent bundles.

      • containsKey

        public boolean containsKey​(String key)
        Determines whether the givenkey is contained in thisResourceBundle or its parent bundles.
        Parameters:
        key - the resourcekey
        Returns:
        true if the givenkey is contained in thisResourceBundle or its parent bundles;false otherwise.
        Throws:
        NullPointerException - ifkey isnull
        Since:
        1.6

      • keySet

        public Set<String> keySet()
        Returns aSet of all keys contained in thisResourceBundle and its parent bundles.
        Returns:
        aSet of all keys contained in thisResourceBundle and its parent bundles.
        Since:
        1.6

      • handleKeySet

        protected Set<String> handleKeySet()
        Returns aSet of the keys containedonly in thisResourceBundle.

        The default implementation returns aSet of the keys returned by thegetKeys method except for the ones for which thehandleGetObject method returnsnull. Once theSet has been created, the value is kept in thisResourceBundle in order to avoid producing the sameSet in subsequent calls. Subclasses can override this method for faster handling.

        Returns:
        aSet of the keys contained only in thisResourceBundle
        Since:
        1.6