Known Direct Subclasses |
Resource bundles contain locale-specific objects. When your program needs a
locale-specific resource, a String
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 a
String
that's used on a button for canceling operations.
In "MyResources" the String
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
the ResourceBundle
class using the
getBundle
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 a ListResourceBundle
that contains
two key/value pairs:
Keys are always 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 }; } }
String
s.
In this example, the keys are "OkKey" and "CancelKey".
In the above example, the values
are also String
s--"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 use getString
to retrieve them:
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 a button1 = new Button(myResources.getString("OkKey")); button2 = new Button(myResources.getString("CancelKey"));
MissingResourceException
.
Besides getString
, ResourceBundle
also provides
a method for getting string arrays, getStringArray
,
as well as a generic getObject
method for any other
type of object. When using getObject
, 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 of ResourceBundle
,
ListResourceBundle
and PropertyResourceBundle
,
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.
If ListResourceBundle
or PropertyResourceBundle
do not suit your needs, you can write your own ResourceBundle
subclass. Your subclasses must override two methods: handleGetObject
and getKeys()
.
The implementation of a ResourceBundle
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 subclasses ListResourceBundle
and
PropertyResourceBundle
are thread-safe.
ResourceBundle.Control
TheResourceBundle.Control
class provides information necessary
to perform the bundle loading process by the getBundle
factory methods that take a ResourceBundle.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 the
getBundle
factory method for details.
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 the {@linkplain #getBundle(String, Locale, ClassLoader,
Control) getBundle
factory method}, clearCache
, ResourceBundle.Control.getTimeToLive
, and ResourceBundle.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 a Map
).
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).
You do not have to restrict yourself to using a single family of // 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")); } }
ResourceBundle
s. 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.
Nested Class Summary
class | ResourceBundle.Control | ResourceBundle.Control defines a set of callback methods
that are invoked by the ResourceBundle.getBundle factory
methods during the bundle loading process. |
Field Summary
protected ResourceBundle | parent | The parent bundle of this bundle. |
Public Constructor Summary
ResourceBundle()
Sole constructor.
|
Public Method Summary
final static void |
clearCache(ClassLoader loader)
Removes all resource bundles from the cache that have been loaded
using the given class loader.
|
final static void |
clearCache()
Removes all resource bundles from the cache that have been loaded
using the caller's class loader.
|
boolean |
containsKey(String key)
Determines whether the given
key is contained in
this ResourceBundle or its parent bundles. |
String |
getBaseBundleName()
Returns the base name of this bundle, if known, or
null if unknown. |
final static 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.
|
final static ResourceBundle | |
final static ResourceBundle | |
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.
|
static ResourceBundle |
getBundle(String baseName, Locale locale, ClassLoader loader)
Gets a resource bundle using the specified base name, locale, and class
loader.
|
final static ResourceBundle |
getBundle(String baseName, ResourceBundle.Control control)
Returns a resource bundle using the specified base name, the
default locale and the specified control.
|
abstract Enumeration<String> |
getKeys()
Returns an enumeration of the keys.
|
Locale |
getLocale()
Returns the locale of this resource bundle.
|
final Object | |
final String | |
final String[] |
getStringArray(String key)
Gets a string array for the given key from this resource bundle or one of its parents.
|
Set<String> |
keySet()
Returns a
Set of all keys contained in this
ResourceBundle and its parent bundles. |
Protected Method Summary
abstract Object | |
Set<String> |
handleKeySet()
Returns a
Set of the keys contained only
in this ResourceBundle . |
void |
Inherited Method Summary
Fields
protected ResourceBundle parent
The parent bundle of this bundle.
The parent bundle is searched by getObject
when this bundle does not contain a particular resource.
Public Constructors
public ResourceBundle ()
Sole constructor. (For invocation by subclass constructors, typically implicit.)
Public Methods
public static final void clearCache (ClassLoader loader)
Removes all resource bundles from the cache that have been loaded using the given class loader.
Parameters
loader | the class loader |
---|
Throws
NullPointerException | if loader is null |
---|
public static final void clearCache ()
Removes all resource bundles from the cache that have been loaded using the caller's class loader.
public boolean containsKey (String key)
Determines whether the given key
is contained in
this ResourceBundle
or its parent bundles.
Parameters
key | the resource key |
---|
Returns
true
if the givenkey
is contained in thisResourceBundle
or its parent bundles;false
otherwise.
Throws
NullPointerException | if key is null |
---|
public String getBaseBundleName ()
Returns the base name of this bundle, if known, or null
if unknown.
If not null, then this is the value of the baseName
parameter
that was passed to the ResourceBundle.getBundle(...)
method
when the resource bundle was loaded.
Returns
- The base name of the resource bundle, as provided to and expected
by the
ResourceBundle.getBundle(...)
methods.
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),
getClassLoader()
is run with the security
privileges of ResourceBundle
. See getBundle
for the
complete description of the resource bundle loading process with a
ResourceBundle.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 a
Locale
inlocales
Throws
NullPointerException | if baseName , locales or
control is null |
---|---|
MissingResourceException | if no resource bundle for the specified base name in any
of the locales can be found. |
IllegalArgumentException | if the given control doesn't perform properly
(e.g., control.getCandidateLocales returns null.)
Note that validation of control is performed as
needed. |
public static final ResourceBundle getBundle (String baseName, Locale locale)
Gets a resource bundle using the specified base name and locale, and the caller's class loader. Calling this method is equivalent to calling
getBundle(baseName, locale, this.getClass().getClassLoader())
,
except that getClassLoader()
is run with the security
privileges of ResourceBundle
.
See getBundle
for a complete description of the search and instantiation strategy.Parameters
baseName | the base name of the resource bundle, a fully qualified class name |
---|---|
locale | the locale for which a resource bundle is desired |
Returns
- a resource bundle for the given base name and locale
Throws
NullPointerException | if baseName or locale is null |
---|---|
MissingResourceException | if no resource bundle for the specified base name can be found |
public static final ResourceBundle getBundle (String baseName)
Gets a resource bundle using the specified base name, the default locale, and the caller's class loader. Calling this method is equivalent to calling
getBundle(baseName, Locale.getDefault(), this.getClass().getClassLoader())
,
except that getClassLoader()
is run with the security
privileges of ResourceBundle
.
See getBundle
for a complete description of the search and instantiation strategy.Parameters
baseName | the base name of the resource bundle, a fully qualified class name |
---|
Returns
- a resource bundle for the given base name and the default locale
Throws
NullPointerException | if baseName is null |
---|---|
MissingResourceException | if no resource bundle for the specified base name can be found |
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 the {@linkplain #getBundle(String, Locale, ClassLoader) getBundle
factory methods with no control
argument}, the given
control
specifies how to locate and instantiate resource
bundles. Conceptually, the bundle loading process with the given
control
is performed in the following steps.
- This factory method looks up the resource bundle in the cache for
the specified
baseName
,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. - 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 {@linkplain PropertyResourceBundle 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. - The
control.getCandidateLocales
method is called with the target locale to get a list of candidateLocale
s for which resource bundles are searched. - The
control.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
Locale("de", "DE")
java.class
Locale("de", "DE")
java.properties
Locale("de")
java.class
Locale("de")
java.properties
Locale("")
java.class
Locale("")
java.properties
- 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 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. - 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. - 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
andfoo/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
.
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 | if baseName , targetLocale ,
loader , or control is
null |
---|---|
MissingResourceException | if no resource bundle for the specified base name can be found |
IllegalArgumentException | if the given control doesn't perform properly
(e.g., control.getCandidateLocales returns null.)
Note that validation of control is performed as
needed. |
public static ResourceBundle getBundle (String baseName, Locale locale, ClassLoader loader)
Gets a resource bundle using the specified base name, locale, and class loader.
This method behaves the same as calling
getBundle(String, Locale, ClassLoader, Control)
passing a
default instance of ResourceBundle.Control
.
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 someLocale
s, 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 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 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 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 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,
Sun's Java SE Runtime Environments do not verify this, and so it is
possible to access PropertyResourceBundle
s by specifying a
path name (using "/") instead of a fully qualified class name (using
".").
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
ResourceBundle
for the ".class" files,
syntactically correct ".properties" files). The default locale is
Locale("en", "GB")
.
Calling getBundle
with the locale arguments below will
instantiate resource bundles as follows:
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.
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 | if baseName , locale , or loader is null |
---|---|
MissingResourceException | if no resource bundle for the specified base name can be found |
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),
getClassLoader()
is run with the security
privileges of ResourceBundle
. See getBundle
for the
complete description of the resource bundle loading process with a
ResourceBundle.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 | if baseName or control is
null |
---|---|
MissingResourceException | if no resource bundle for the specified base name can be found |
IllegalArgumentException | if the given control doesn't perform properly
(e.g., control.getCandidateLocales returns null.)
Note that validation of control is performed as
needed. |
public abstract Enumeration<String> getKeys ()
Returns an enumeration of the keys.
Returns
- an
Enumeration
of the keys contained in thisResourceBundle
and its parent bundles.
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
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 using
handleGetObject
.
If not successful, and the parent resource bundle is not null,
it calls the parent's getObject
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 | if key is null |
---|---|
MissingResourceException | if no object for the given key can be found |
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 | if key is null |
---|---|
MissingResourceException | if no object for the given key can be found |
ClassCastException | if the object found for the given key is not a string |
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 | if key is null |
---|---|
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 |
Protected Methods
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 | if key is null |
---|
protected Set<String> handleKeySet ()
Returns a Set
of the keys contained only
in this ResourceBundle
.
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.
Returns
- a
Set
of the keys contained only in thisResourceBundle
protected void setParent (ResourceBundle parent)
Sets the parent bundle of this bundle.
The parent bundle is searched by getObject
when this bundle does not contain a particular resource.
Parameters
parent | this bundle's parent bundle. |
---|