Resource bundles in named modules may be encapsulated. When the resource bundle is loaded from a service provider, the caller module must have an appropriate uses clause in its module descriptor to declare that the module uses of ResourceBundleProvider for the named resource bundle. Otherwise, it will load the resource bundles that are local in the given module as if calling Module.getResourceAsStream(String) or that are visible to the class loader of the given module as if calling ClassLoader.getResourceAsStream(String). When the resource bundle is loaded from the specified module, it is subject to the encapsulation rules specified by Module.getResourceAsStream.

If the given module is an unnamed module, then this method is equivalent to calling getBundle(baseName, targetLocale, module.getClassLoader() to load resource bundles that are visible to the class loader of the given unnamed module. Custom ResourceBundleControlProvider implementations, if present, will only be invoked if the specified module is an unnamed module.

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:

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    getBundle(baseName, targetLocale, callerModule);

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    getBundle(baseName, targetLocale, loader, control);

Resource Bundle Search and Loading Strategy

getBundle uses the base name, the specified locale, and the default locale (obtained from Locale.getDefault) to generate a sequence of candidate 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
 

 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 some Locales, 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 of getCandidateLocales for details.

getBundle then iterates over the candidate bundle names to find the first one for which it can instantiate 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 the result 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 using ClassLoader.getResource. (Note that a "resource" in the sense of getResource 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 new PropertyResourceBundle instance from its contents. If successful, this instance becomes the result 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's getFallbackLocale 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, a MissingResourceException is thrown.

Once a result resource bundle has been found, its parent 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's setParent 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:The baseName 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 access PropertyResourceBundles 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

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

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.

1. This factory method looks up the resource bundle in the cache for the specified baseName, targetLocale and loader. 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. The control.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 and property-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. The control.getCandidateLocales method is called with the target locale to get a list of candidate Locales for which resource bundles are searched.
4. The control.newBundle method is called to instantiate a ResourceBundle 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 the newBundle method returns a ResourceBundle instance or the iteration has used up all the combinations. For example, if the candidate locales are Locale("de", "DE"), Locale("de") and Locale("") and the formats are "java.class" and "java.properties", then the following is the sequence of locale-format combinations to be used to call control.newBundle.

   locale-format combinations for newBundle

   Index	Locale	format
   1	Locale("de", "DE")	java.class
   2	Locale("de", "DE")	java.properties
   3	Locale("de")	java.class
   4	Locale("de")	java.properties
   5	Locale("")	java.class
   6	Locale("")	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 for Locale("")), and the candidate locale list only contained Locale(""), 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. The control.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, its parent 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 the control.newBundle method. If the time-to-live period of the resource bundle found in the cache has expired, the factory method calls the control.needsReload method to determine whether the resource bundle needs to be reloaded. If reloading is required, the factory method calls control.newBundle to reload the resource bundle. If control.newBundle returns null, 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 by control.

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

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

Conditions:

• Base bundle name: foo.bar.Messages
• Requested Locale: Locale.ITALY
• Default Locale: Locale.FRENCH
• Available resource bundles: foo/bar/Messages_fr.properties and foo/bar/Messages.properties

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

• class foo.bar.Messages_it_IT
• file foo/bar/Messages_it_IT.properties
• class foo.bar.Messages_it
• file foo/bar/Messages_it.properties
• class foo.bar.Messages
• file foo/bar/Messages.properties

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

• class foo.bar.Messages_fr
• file foo/bar/Messages_fr.properties
• class foo.bar.Messages
• file foo/bar/Messages.properties

getBundle finds foo/bar/Messages_fr.properties and creates a ResourceBundle instance. Then, getBundle sets up its parent chain from the list of the candidate locales. Only foo/bar/Messages.properties is found in the list and getBundle creates a ResourceBundle instance that becomes the parent of the instance for foo/bar/Messages_fr.properties.

The default implementation returns a Set of the keys returned by the getKeys method except for the ones for which the handleGetObject method returns null. Once the Set has been created, the value is kept in this ResourceBundle in order to avoid producing the same Set in subsequent calls. Subclasses can override this method for faster handling.