/*
 * @(#)ResourceBundle.java	1.86 06/03/30
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/*
 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996 - 1999 - All Rights Reserved
 *
 * The original version of this source code and documentation
 * is copyrighted and owned by Taligent, Inc., a wholly-owned
 * subsidiary of IBM. These materials are provided under terms
 * of a License Agreement between Taligent and Sun. This technology
 * is protected by multiple US and International patents.
 *
 * This notice and attribution to Taligent may not be removed.
 * Taligent is a registered trademark of Taligent, Inc.
 *
 */

package java.util;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.jar.JarEntry;


/**
 *
 * Resource bundles contain locale-specific objects.
 * When your program needs a locale-specific resource,
 * a <code>String</code> 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.
 *
 * <p>
 * This allows you to write programs that can:
 * <UL type=SQUARE>
 * <LI> be easily localized, or translated, into different languages
 * <LI> handle multiple locales at once
 * <LI> be easily modified later to support even more locales
 * </UL>
 *
 * <P>
 * 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".
 *
 * <P>
 * 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
 * <code>String</code> that's used on a button for canceling operations.
 * In "MyResources" the <code>String</code> may contain "Cancel" and in
 * "MyResources_de" it may contain "Abbrechen".
 *
 * <P>
 * 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.
 *
 * <P>
 * When your program needs a locale-specific object, it loads
 * the <code>ResourceBundle</code> class using the
 * {@link #getBundle(java.lang.String, java.util.Locale) getBundle}
 * method:
 * <blockquote>
 * <pre>
 * ResourceBundle myResources =
 *      ResourceBundle.getBundle("MyResources", currentLocale);
 * </pre>
 * </blockquote>
 *
 * <P>
 * Resource bundles contain key/value pairs. The keys uniquely
 * identify a locale-specific object in the bundle. Here's an
 * example of a <code>ListResourceBundle</code> that contains
 * two key/value pairs:
 * <blockquote>
 * <pre>
 * 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
 *        };
 *     }
 * }
 * </pre>
 * </blockquote>
 * Keys are always <code>String</code>s.
 * In this example, the keys are "OkKey" and "CancelKey".
 * In the above example, the values
 * are also <code>String</code>s--"OK" and "Cancel"--but
 * they don't have to be. The values can be any type of object.
 *
 * <P>
 * You retrieve an object from resource bundle using the appropriate
 * getter method. Because "OkKey" and "CancelKey"
 * are both strings, you would use <code>getString</code> to retrieve them:
 * <blockquote>
 * <pre>
 * button1 = new Button(myResources.getString("OkKey"));
 * button2 = new Button(myResources.getString("CancelKey"));
 * </pre>
 * </blockquote>
 * 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 <code>MissingResourceException</code>.
 *
 * <P>
 * Besides <code>getString</code>, <code>ResourceBundle</code> also provides
 * a method for getting string arrays, <code>getStringArray</code>,
 * as well as a generic <code>getObject</code> method for any other
 * type of object. When using <code>getObject</code>, you'll
 * have to cast the result to the appropriate type. For example:
 * <blockquote>
 * <pre>
 * int[] myIntegers = (int[]) myResources.getObject("intList");
 * </pre>
 * </blockquote>
 *
 * <P>
 * The Java Platform provides two subclasses of <code>ResourceBundle</code>,
 * <code>ListResourceBundle</code> and <code>PropertyResourceBundle</code>,
 * that provide a fairly simple way to create resources.
 * As you saw briefly in a previous example, <code>ListResourceBundle</code>
 * manages its resource as a list of key/value pairs.
 * <code>PropertyResourceBundle</code> uses a properties file to manage
 * its resources.
 *
 * <p>
 * If <code>ListResourceBundle</code> or <code>PropertyResourceBundle</code>
 * do not suit your needs, you can write your own <code>ResourceBundle</code>
 * subclass.  Your subclasses must override two methods: <code>handleGetObject</code>
 * and <code>getKeys()</code>.
 *
 * <h4>ResourceBundle.Control</h4>
 *
 * The {@link ResourceBundle.Control} class provides information necessary
 * to perform the bundle loading process by the <code>getBundle</code>
 * factory methods that take a <code>ResourceBundle.Control</code>
 * 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
 * {@link #getBundle(String, Locale, ClassLoader, Control) getBundle}
 * factory method for details.
 *
 * <h4>Cache Management</h4>
 *
 * Resource bundle instances created by the <code>getBundle</code> factory
 * methods are cached by default, and the factory methods return the same
 * resource bundle instance multiple times if it has been
 * cached. <code>getBundle</code> 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) <code>getBundle</code> factory method}, {@link
 * #clearCache(ClassLoader) clearCache}, {@link
 * Control#getTimeToLive(String, Locale)
 * ResourceBundle.Control.getTimeToLive}, and {@link
 * Control#needsReload(String, Locale, String, ClassLoader, ResourceBundle,
 * long) ResourceBundle.Control.needsReload} for details.
 *
 * <h4>Example</h4>
 *
 * The following is a very simple example of a <code>ResourceBundle</code>
 * subclass, <code>MyResources</code>, that manages two resources (for a larger number of
 * resources you would probably use a <code>Map</code>).
 * Notice that you don't need to supply a value if 
 * a "parent-level" <code>ResourceBundle</code> handles the same
 * key with the same value (as for the okKey below).
 * <blockquote>
 * <pre>
 * // 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&lt;String&gt; getKeys() {
 *         return Collections.enumeration(keySet());
 *     }
 * 
 *     // Overrides handleKeySet() so that the getKeys() implementation
 *     // can rely on the keySet() value.
 *     protected Set&lt;String&gt; handleKeySet() {
 *         return new HashSet&lt;String&gt;(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&lt;String&gt; handleKeySet() {
 *         return new HashSet&lt;String&gt;(Arrays.asList("cancelKey"));
 *     }
 * }
 * </pre>
 * </blockquote>
 * You do not have to restrict yourself to using a single family of
 * <code>ResourceBundle</code>s. For example, you could have a set of bundles for
 * exception messages, <code>ExceptionResources</code>
 * (<code>ExceptionResources_fr</code>, <code>ExceptionResources_de</code>, ...),
 * and one for widgets, <code>WidgetResource</code> (<code>WidgetResources_fr</code>,
 * <code>WidgetResources_de</code>, ...); breaking up the resources however you like.
 *
 * @see ListResourceBundle
 * @see PropertyResourceBundle
 * @see MissingResourceException
 * @since JDK1.1
 */
public abstract class ResourceBundle {

    /** initial size of the bundle cache */
    private static final int INITIAL_CACHE_SIZE = 32;

    /** constant indicating that no resource bundle exists */
    private static final ResourceBundle NONEXISTENT_BUNDLE = new ResourceBundle() {
	    public Enumeration<String> getKeys() { return null; }
	    protected Object handleGetObject(String key) { return null; }
	    public String toString() { return "NONEXISTENT_BUNDLE"; }
	};


    /**
     * The cache is a map from cache keys (with bundle base name, locale, and
     * class loader) to either a resource bundle or NONEXISTENT_BUNDLE wrapped by a
     * BundleReference.
     *
     * The cache is a ConcurrentMap, allowing the cache to be searched
     * concurrently by multiple threads.  This will also allow the cache keys
     * to be reclaimed along with the ClassLoaders they reference.
     *
     * This variable would be better named "cache", but we keep the old
     * name for compatibility with some workarounds for bug 4212439.
     */
    private static final ConcurrentMap<CacheKey, BundleReference> cacheList
	= new ConcurrentHashMap<CacheKey, BundleReference>(INITIAL_CACHE_SIZE);

    /**
     * This ConcurrentMap is used to keep multiple threads from loading the
     * same bundle concurrently.  The table entries are <CacheKey, Thread>
     * where CacheKey is the key for the bundle that is under construction
     * and Thread is the thread that is constructing the bundle.
     * This list is manipulated in findBundleInCache and putBundleInCache.
     */
    private static final ConcurrentMap<CacheKey, Thread> underConstruction
	= new ConcurrentHashMap<CacheKey, Thread>();

    /**
     * Queue for reference objects referring to class loaders or bundles.
     */
    private static final ReferenceQueue referenceQueue = new ReferenceQueue();

    /**
     * The parent bundle of this bundle.
     * The parent bundle is searched by {@link #getObject getObject}
     * when this bundle does not contain a particular resource.
     */
    protected ResourceBundle parent = null;

    /**
     * The locale for this bundle.
     */
    private Locale locale = null;

    /**
     * The base bundle name for this bundle.
     */
    private String name;

    /**
     * The flag indicating this bundle has expired in the cache.
     */
    private volatile boolean expired;

    /**
     * The back link to the cache key. null if this bundle isn't in
     * the cache (yet) or has expired.
     */
    private volatile CacheKey cacheKey;

    /**
     * A Set of the keys contained only in this ResourceBundle.
     */
    private volatile Set<String> keySet;

    /**
     * Sole constructor.  (For invocation by subclass constructors, typically
     * implicit.)
     */
    public ResourceBundle() {
    }

    /**
     * Gets a string for the given key from this resource bundle or one of its parents.
     * Calling this method is equivalent to calling
     * <blockquote>
     * <code>(String) {@link #getObject(java.lang.String) getObject}(key)</code>.
     * </blockquote>
     *
     * @param key the key for the desired string
     * @exception NullPointerException if <code>key</code> is <code>null</code>
     * @exception MissingResourceException if no object for the given key can be found
     * @exception ClassCastException if the object found for the given key is not a string
     * @return the string for the given key
     */
    public final String getString(String key) {
        return (String) getObject(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
     * <blockquote>
     * <code>(String[]) {@link #getObject(java.lang.String) getObject}(key)</code>.
     * </blockquote>
     *
     * @param key the key for the desired string array
     * @exception NullPointerException if <code>key</code> is <code>null</code>
     * @exception MissingResourceException if no object for the given key can be found
     * @exception ClassCastException if the object found for the given key is not a string array
     * @return the string array for the given key
     */
    public final String[] getStringArray(String key) {
        return (String[]) getObject(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
     * {@link #handleGetObject(java.lang.String) handleGetObject}.
     * If not successful, and the parent resource bundle is not null,
     * it calls the parent's <code>getObject</code> method.
     * If still not successful, it throws a MissingResourceException.
     *
     * @param key the key for the desired object
     * @exception NullPointerException if <code>key</code> is <code>null</code>
     * @exception MissingResourceException if no object for the given key can be found
     * @return the object for the given key
     */
    public final Object getObject(String key) {
        Object obj = handleGetObject(key);
        if (obj == null) {
            if (parent != null) {
                obj = parent.getObject(key);
            }
            if (obj == null)
                throw new MissingResourceException("Can't find resource for bundle "
                                                   +this.getClass().getName()
                                                   +", key "+key,
                                                   this.getClass().getName(),
                                                   key);
        }
        return obj;
    }

    /**
     * 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.
     *
     * @return the locale of this resource bundle
     */
    public Locale getLocale() {
        return locale;
    }

    /*
     * Automatic determination of the ClassLoader to be used to load
     * resources on behalf of the client.  N.B. The client is getLoader's
     * caller's caller.
     */
    private static ClassLoader getLoader() {
        Class[] stack = getClassContext();
        /* Magic number 2 identifies our caller's caller */
        Class c = stack[2];
        ClassLoader cl = (c == null) ? null : c.getClassLoader();
        if (cl == null) {
	    // When the caller's loader is the boot class loader, cl is null
	    // here. In that case, ClassLoader.getSystemClassLoader() may
	    // return the same class loader that the application is
	    // using. We therefore use a wrapper ClassLoader to create a
	    // separate scope for bundles loaded on behalf of the Java
	    // runtime so that these bundles cannot be returned from the
	    // cache to the application (5048280).
	    cl = RBClassLoader.INSTANCE;
        }
        return cl;
    }

    private static native Class[] getClassContext();

    /**
     * A wrapper of ClassLoader.getSystemClassLoader().
     */
    private static class RBClassLoader extends ClassLoader {
	private static final RBClassLoader INSTANCE = AccessController.doPrivileged(
		    new PrivilegedAction<RBClassLoader>() {
			public RBClassLoader run() {
			    return new RBClassLoader();
			}
		    });
	private static final ClassLoader loader = ClassLoader.getSystemClassLoader();

	private RBClassLoader() {
	}
	public Class<?> loadClass(String name) throws ClassNotFoundException {
	    if (loader != null) {
		return loader.loadClass(name);
	    }
	    return Class.forName(name);
	}
	public URL getResource(String name) {
	    if (loader != null) {
		return loader.getResource(name);
	    }
	    return ClassLoader.getSystemResource(name);
	}
	public InputStream getResourceAsStream(String name) {
	    if (loader != null) {
		return loader.getResourceAsStream(name);
	    }
	    return ClassLoader.getSystemResourceAsStream(name);
	}
    }

    /**
     * Sets the parent bundle of this bundle.
     * The parent bundle is searched by {@link #getObject getObject}
     * when this bundle does not contain a particular resource.
     *
     * @param parent this bundle's parent bundle.
     */
    protected void setParent(ResourceBundle parent) {
	assert parent != NONEXISTENT_BUNDLE;
        this.parent = parent;
    }

    /**
     * Key used for cached resource bundles.  The key checks the base
     * name, the locale, and the class loader to determine if the
     * resource is a match to the requested one. The loader may be
     * null, but the base name and the locale must have a non-null
     * value.
     */
    private static final class CacheKey implements Cloneable {
	// These three are the actual keys for lookup in Map.
        private String name;
        private Locale locale;
        private LoaderReference loaderRef;

	// bundle format which is necessary for calling
	// Control.needsReload().
	private String format;

	// These time values are in CacheKey so that NONEXISTENT_BUNDLE
	// doesn't need to be cloned for caching.

	// The time when the bundle has been loaded
	private volatile long loadTime;

	// The time when the bundle expires in the cache, or either
	// Control.TTL_DONT_CACHE or Control.TTL_NO_EXPIRATION_CONTROL.
	private volatile long expirationTime;

	// Placeholder for an error report by a Throwable
	private Throwable cause;

	// Hash code value cache to avoid recalculating the hash code
	// of this instance.
        private int hashCodeCache;

	CacheKey(String baseName, Locale locale, ClassLoader loader) {
            this.name = baseName;
            this.locale = locale;
            if (loader == null) {
                this.loaderRef = null;
            } else {
                loaderRef = new LoaderReference(loader, referenceQueue, this);
            }
	    calculateHashCode();
	}

	String getName() {
	    return name;
	}

	CacheKey setName(String baseName) {
	    if (!this.name.equals(baseName)) {
		this.name = baseName;
		calculateHashCode();
	    }
	    return this;
	}

	Locale getLocale() {
	    return locale;
	}

	CacheKey setLocale(Locale locale) {
	    if (!this.locale.equals(locale)) {
		this.locale = locale;
		calculateHashCode();
	    }
	    return this;
	}

	ClassLoader getLoader() {
	    return (loaderRef != null) ? loaderRef.get() : null;
	}

        public boolean equals(Object other) {
            if (this == other) {
                return true;
            }
            try {
                final CacheKey otherEntry = (CacheKey)other;
                //quick check to see if they are not equal
                if (hashCodeCache != otherEntry.hashCodeCache) {
                    return false;
                }
                //are the names the same?
                if (!name.equals(otherEntry.name)) {
                    return false;
                }
                // are the locales the same?
		if (!locale.equals(otherEntry.locale)) {
		    return false;
                }
                //are refs (both non-null) or (both null)?
                if (loaderRef == null) {
                    return otherEntry.loaderRef == null;
                }
		ClassLoader loader = loaderRef.get();
		return (otherEntry.loaderRef != null)
                        // with a null reference we can no longer find
                        // out which class loader was referenced; so
                        // treat it as unequal
                        && (loader != null)
                        && (loader == otherEntry.loaderRef.get());
            } catch (NullPointerException e) {
            } catch (ClassCastException e) {
            }
	    return false;
        }

        public int hashCode() {
            return hashCodeCache;
        }

	private void calculateHashCode() {
            hashCodeCache = name.hashCode() << 3;
	    hashCodeCache ^= locale.hashCode();
	    ClassLoader loader = getLoader();
	    if (loader != null) {
                hashCodeCache ^= loader.hashCode();
            }
	}

        public Object clone() {
            try {
                CacheKey clone = (CacheKey) super.clone();
                if (loaderRef != null) {
                    clone.loaderRef = new LoaderReference(loaderRef.get(),
							  referenceQueue, clone);
                }
		// Clear the reference to a Throwable
		clone.cause = null;
                return clone;
            } catch (CloneNotSupportedException e) {
                //this should never happen
                throw new InternalError();
            }
        }

	String getFormat() {
	    return format;
	}

	void setFormat(String format) {
	    this.format = format;
	}

	private void setCause(Throwable cause) {
	    if (this.cause == null) {
		this.cause = cause;
	    } else {
		// Override the cause if the previous one is
		// ClassNotFoundException.
		if (this.cause instanceof ClassNotFoundException) {
		    this.cause = cause;
		}
	    }
	}

	private Throwable getCause() {
	    return cause;
	}

	public String toString() {
	    String l = locale.toString();
	    if (l.length() == 0) {
		if (locale.getVariant().length() != 0) {
		    l = "__" + locale.getVariant();
		} else {
		    l = "\"\"";
		}
	    }
	    return "CacheKey[" + name + ", lc=" + l + ", ldr=" + getLoader()
		+ "(format=" + format + ")]";
	}
    }

    /**
     * The common interface to get a CacheKey in LoaderReference and
     * BundleReference.
     */
    private static interface CacheKeyReference {
	public CacheKey getCacheKey();
    }

    /**
     * References to class loaders are weak references, so that they can be
     * garbage collected when nobody else is using them. The ResourceBundle
     * class has no reason to keep class loaders alive.
     */
    private static final class LoaderReference extends WeakReference<ClassLoader>
					       implements CacheKeyReference {
        private CacheKey cacheKey;

        LoaderReference(ClassLoader referent, ReferenceQueue q, CacheKey key) {
            super(referent, q);
            cacheKey = key;
        }

        public CacheKey getCacheKey() {
            return cacheKey;
        }
    }

    /**
     * References to bundles are soft references so that they can be garbage
     * collected when they have no hard references.
     */
    private static final class BundleReference extends SoftReference<ResourceBundle>
					       implements CacheKeyReference {
	private CacheKey cacheKey;

 	BundleReference(ResourceBundle referent, ReferenceQueue q, CacheKey key) {
	    super(referent, q);
	    cacheKey = key;
	}

	public CacheKey getCacheKey() {
	    return cacheKey;
	}
    }

    /**
     * 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
     * <blockquote>
     * <code>getBundle(baseName, Locale.getDefault(), this.getClass().getClassLoader())</code>,
     * </blockquote>
     * except that <code>getClassLoader()</code> is run with the security
     * privileges of <code>ResourceBundle</code>.
     * See {@link #getBundle(String, Locale, ClassLoader) getBundle}
     * for a complete description of the search and instantiation strategy.
     *
     * @param baseName the base name of the resource bundle, a fully qualified class name
     * @exception java.lang.NullPointerException
     *     if <code>baseName</code> is <code>null</code>
     * @exception MissingResourceException
     *     if no resource bundle for the specified base name can be found
     * @return a resource bundle for the given base name and the default locale
     */
    public static final ResourceBundle getBundle(String baseName)
    {
        return getBundleImpl(baseName, Locale.getDefault(),
			     /* must determine loader here, else we break stack invariant */
			     getLoader(),
			     Control.INSTANCE);
    }

    /**
     * Returns a resource bundle using the specified base name, the
     * default locale and the specified control. Calling this method
     * is equivalent to calling
     * <pre>
     * getBundle(baseName, Locale.getDefault(),
     *           this.getClass().getClassLoader(), control),
     * </pre>
     * except that <code>getClassLoader()</code> is run with the security
     * privileges of <code>ResourceBundle</code>.  See {@link
     * #getBundle(String, Locale, ClassLoader, Control) getBundle} for the
     * complete description of the resource bundle loading process with a
     * <code>ResourceBundle.Control</code>.
     *
     * @param baseName
     *        the base name of the resource bundle, a fully qualified class
     *        name
     * @param control
     *        the control which gives information for the resource bundle
     *        loading process
     * @return a resource bundle for the given base name and the default
     *        locale
     * @exception NullPointerException
     *        if <code>baseName</code> or <code>control</code> is
     *        <code>null</code>
     * @exception MissingResourceException
     *        if no resource bundle for the specified base name can be found
     * @exception IllegalArgumentException
     *        if the given <code>control</code> doesn't perform properly
     *        (e.g., <code>control.getCandidateLocales</code> returns null.) 
     *        Note that validation of <code>control</code> is performed as
     *        needed.
     * @since 1.6
     */
    public static final ResourceBundle getBundle(String baseName,
						 Control control) {
	return getBundleImpl(baseName, Locale.getDefault(),
			     /* must determine loader here, else we break stack invariant */
			     getLoader(),
			     control);
    }

    /**
     * Gets a resource bundle using the specified base name and locale,
     * and the caller's class loader. Calling this method is equivalent to calling
     * <blockquote>
     * <code>getBundle(baseName, locale, this.getClass().getClassLoader())</code>,
     * </blockquote>
     * except that <code>getClassLoader()</code> is run with the security
     * privileges of <code>ResourceBundle</code>.
     * See {@link #getBundle(String, Locale, ClassLoader) getBundle}
     * for a complete description of the search and instantiation strategy.
     *
     * @param baseName
     *        the base name of the resource bundle, a fully qualified class name
     * @param locale
     *        the locale for which a resource bundle is desired
     * @exception NullPointerException
     *        if <code>baseName</code> or <code>locale</code> is <code>null</code>
     * @exception MissingResourceException
     *        if no resource bundle for the specified base name can be found
     * @return a resource bundle for the given base name and locale
     */
    public static final ResourceBundle getBundle(String baseName,
						 Locale locale)
    {
        return getBundleImpl(baseName, locale,
			     /* must determine loader here, else we break stack invariant */
			     getLoader(),
			     Control.INSTANCE);
    }

    /**
     * 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
     * <pre>
     * getBundle(baseName, targetLocale, this.getClass().getClassLoader(),
     *           control),
     * </pre>
     * except that <code>getClassLoader()</code> is run with the security
     * privileges of <code>ResourceBundle</code>.  See {@link
     * #getBundle(String, Locale, ClassLoader, Control) getBundle} for the
     * complete description of the resource bundle loading process with a
     * <code>ResourceBundle.Control</code>.
     *
     * @param baseName
     *        the base name of the resource bundle, a fully qualified
     *        class name
     * @param targetLocale
     *        the locale for which a resource bundle is desired
     * @param control
     *        the control which gives information for the resource
     *        bundle loading process
     * @return a resource bundle for the given base name and a
     *        <code>Locale</code> in <code>locales</code>
     * @exception NullPointerException
     *        if <code>baseName</code>, <code>locales</code> or
     *        <code>control</code> is <code>null</code>
     * @exception MissingResourceException
     *        if no resource bundle for the specified base name in any
     *        of the <code>locales</code> can be found.
     * @exception IllegalArgumentException
     *        if the given <code>control</code> doesn't perform properly
     *        (e.g., <code>control.getCandidateLocales</code> returns null.) 
     *        Note that validation of <code>control</code> is performed as
     *        needed.
     * @since 1.6
     */
    public static final ResourceBundle getBundle(String baseName, Locale targetLocale,
						 Control control) {
	return getBundleImpl(baseName, targetLocale,
			     /* must determine loader here, else we break stack invariant */
			     getLoader(),
			     control);
    }

    /**
     * Gets a resource bundle using the specified base name, locale, and class loader.
     *
     * <p><a name="default_behavior"/>
     * Conceptually, <code>getBundle</code> uses the following strategy for locating and instantiating
     * resource bundles:
     * <p>
     * <code>getBundle</code> uses the base name, the specified locale, and the default
     * locale (obtained from {@link java.util.Locale#getDefault() Locale.getDefault})
     * to generate a sequence of <a name="candidates"><em>candidate bundle names</em></a>.
     * If the specified locale's language, country, and variant are all empty
     * strings, then the base name is the only candidate bundle name.
     * Otherwise, the following sequence is generated from the attribute
     * values of the specified locale (language1, country1, and variant1)
     * and of the default locale (language2, country2, and variant2):
     * <ul>
     * <li> baseName + "_" + language1 + "_" + country1 + "_" + variant1
     * <li> baseName + "_" + language1 + "_" + country1
     * <li> baseName + "_" + language1
     * <li> baseName + "_" + language2 + "_" + country2 + "_" + variant2
     * <li> baseName + "_" + language2 + "_" + country2
     * <li> baseName + "_" + language2
     * <li> baseName
     * </ul>
     * <p>
     * Candidate bundle names where the final component is an empty string are omitted.
     * For example, if country1 is an empty string, the second candidate bundle name is omitted.
     *
     * <p>
     * <code>getBundle</code> then iterates over the candidate bundle names to find the first
     * one for which it can <em>instantiate</em> an actual resource bundle. For each candidate
     * bundle name, it attempts to create a resource bundle:
     * <ul>
     * <li>
     * First, it attempts to load a class using the candidate bundle 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,
     * <code>getBundle</code> creates a new instance of this class and uses it as the <em>result
     * resource bundle</em>.
     * <li>
     * Otherwise, <code>getBundle</code> attempts to locate a property resource file.
     * 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
     * {@link java.lang.ClassLoader#getResource(java.lang.String) ClassLoader.getResource}.
     * (Note that a "resource" in the sense of <code>getResource</code> 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
     * {@link PropertyResourceBundle} instance from its contents.
     * If successful, this instance becomes the <em>result resource bundle</em>.
     * </ul>
     *
     * <p>
     * If no result resource bundle has been found, a <code>MissingResourceException</code>
     * is thrown.
     *
     * <p><a name="parent_chain"/>
     * Once a result resource bundle has been found, its <em>parent chain</em> is instantiated.
     * <code>getBundle</code> iterates over the candidate bundle names that can be
     * obtained by successively removing variant, country, and language
     * (each time with the preceding "_") from the bundle name of the result resource bundle.
     * As above, candidate bundle names where the final component is an empty string are omitted.
     * With each of the candidate bundle names it attempts to instantiate a resource bundle, as
     * described above.
     * Whenever it succeeds, it calls the previously instantiated resource
     * bundle's {@link #setParent(java.util.ResourceBundle) setParent} method
     * with the new resource bundle, unless the previously instantiated resource
     * bundle already has a non-null parent.
     *
     * <p>
     * <code>getBundle</code> caches instantiated resource bundles and
     * may return the same resource bundle instance multiple
     * times.
     *
     * <p>
     * The <code>baseName</code> 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 <code>PropertyResourceBundle</code>s by specifying a
     * path name (using "/") instead of a fully qualified class name (using ".").
     *
     * <p><a name="default_behavior_example"/>
     * <strong>Example:</strong><br>The following class and property files are provided:
     * <pre>
     *     MyResources.class
     *     MyResources.properties
     *     MyResources_fr.properties
     *     MyResources_fr_CH.class
     *     MyResources_fr_CH.properties
     *     MyResources_en.properties
     *     MyResources_es_ES.class
     * </pre>
     * The contents of all files are valid (that is, public non-abstract subclasses of <code>ResourceBundle</code> for
     * the ".class" files, syntactically correct ".properties" files).
     * The default locale is <code>Locale("en", "GB")</code>.
     * <p>
     * Calling <code>getBundle</code> with the shown locale argument values instantiates
     * resource bundles from the following sources:
     * <ul>
     * <li>Locale("fr", "CH"): result MyResources_fr_CH.class, parent MyResources_fr.properties, parent MyResources.class
     * <li>Locale("fr", "FR"): result MyResources_fr.properties, parent MyResources.class
     * <li>Locale("de", "DE"): result MyResources_en.properties, parent MyResources.class
     * <li>Locale("en", "US"): result MyResources_en.properties, parent MyResources.class
     * <li>Locale("es", "ES"): result MyResources_es_ES.class, parent MyResources.class
     * </ul>
     * <p>The file MyResources_fr_CH.properties is never used because it is hidden by
     * MyResources_fr_CH.class. Likewise, MyResources.properties is also hidden by
     * MyResources.class.
     *
     * @param baseName the base name of the resource bundle, a fully qualified class name
     * @param locale the locale for which a resource bundle is desired
     * @param loader the class loader from which to load the resource bundle
     * @return a resource bundle for the given base name and locale
     * @exception java.lang.NullPointerException
     *        if <code>baseName</code>, <code>locale</code>, or <code>loader</code> is <code>null</code>
     * @exception MissingResourceException
     *        if no resource bundle for the specified base name can be found
     * @since 1.2
     */
    public static ResourceBundle getBundle(String baseName, Locale locale,
                                           ClassLoader loader)
    {
        if (loader == null) {
            throw new NullPointerException();
        }
        return getBundleImpl(baseName, locale, loader, Control.INSTANCE);
    }

    /**
     * Returns a resource bundle using the specified base name, target
     * locale, class loader and control. Unlike the {@linkplain
     * #getBundle(String, Locale, ClassLoader) <code>getBundle</code>
     * factory methods with no <code>control</code> argument}, the given
     * <code>control</code> specifies how to locate and instantiate resource
     * bundles. Conceptually, the bundle loading process with the given
     * <code>control</code> is performed in the following steps.
     *
     * <p>
     * <ol>
     * <li>This factory method looks up the resource bundle in the cache for
     * the specified <code>baseName</code>, <code>targetLocale</code> and
     * <code>loader</code>.  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.</li>
     *
     * <li>The {@link ResourceBundle.Control#getFormats(String)
     * control.getFormats} method is called to get resource bundle formats
     * to produce bundle or resource names. The strings
     * <code>"java.class"</code> and <code>"java.properties"</code>
     * designate class-based and {@linkplain PropertyResourceBundle
     * property}-based resource bundles, respectively. Other strings
     * starting with <code>"java."</code> are reserved for future extensions
     * and must not be used for application-defined formats. Other strings
     * designate application-defined formats.</li>
     *
     * <li>The {@link ResourceBundle.Control#getCandidateLocales(String,
     * Locale) control.getCandidateLocales} method is called with the target
     * locale to get a list of <em>candidate <code>Locale</code>s</em> for
     * which resource bundles are searched.</li>
     *
     * <li>The {@link ResourceBundle.Control#newBundle(String, Locale,
     * String, ClassLoader, boolean) control.newBundle} method is called to
     * instantiate a <code>ResourceBundle</code> 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 <code>newBundle</code> method
     * returns a <code>ResourceBundle</code> instance or the iteration has
     * used up all the combinations. For example, if the candidate locales
     * are <code>Locale("de", "DE")</code>, <code>Locale("de")</code> and
     * <code>Locale("")</code> and the formats are <code>"java.class"</code>
     * and <code>"java.properties"</code>, then the following is the
     * sequence of locale-format combinations to be used to call
     * <code>control.newBundle</code>.
     *
     * <table style="width: 50%; text-align: left; margin-left: 40px;"
     *  border="0" cellpadding="2" cellspacing="2">
     * <tbody><code>
     * <tr>
     * <td
     * style="vertical-align: top; text-align: left; font-weight: bold; width: 50%;">Locale<br>
     * </td>
     * <td
     * style="vertical-align: top; text-align: left; font-weight: bold; width: 50%;">format<br>
     * </td>
     * </tr>
     * <tr>
     * <td style="vertical-align: top; width: 50%;">Locale("de", "DE")<br>
     * </td>
     * <td style="vertical-align: top; width: 50%;">java.class<br>
     * </td>
     * </tr>
     * <tr>
     * <td style="vertical-align: top; width: 50%;">Locale("de", "DE")</td>
     * <td style="vertical-align: top; width: 50%;">java.properties<br>
     * </td>
     * </tr>
     * <tr>
     * <td style="vertical-align: top; width: 50%;">Locale("de")</td>
     * <td style="vertical-align: top; width: 50%;">java.class</td>
     * </tr>
     * <tr>
     * <td style="vertical-align: top; width: 50%;">Locale("de")</td>
     * <td style="vertical-align: top; width: 50%;">java.properties</td>
     * </tr>
     * <tr>
     * <td style="vertical-align: top; width: 50%;">Locale("")<br>
     * </td>
     * <td style="vertical-align: top; width: 50%;">java.class</td>
     * </tr>
     * <tr>
     * <td style="vertical-align: top; width: 50%;">Locale("")</td>
     * <td style="vertical-align: top; width: 50%;">java.properties</td>
     * </tr>
     * </code></tbody>
     * </table>
     * </li>
     *
     * <li>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 <code>Locale("")</code>), and the candidate locale list only contained
     * <code>Locale("")</code>, 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.</li>
     *
     * <li>The {@link ResourceBundle.Control#getFallbackLocale(String,
     * Locale) 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.</li>
     *
     * <li>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 <a
     * href="./ResourceBundle.html#parent_chain">parent chain</a> is
     * instantiated based on the list of candidate locales from which it was
     * found. Finally, the bundle is returned to the caller.</li>
     *
     *
     * </ol>
     *
     * <p>During the resource bundle loading process above, this factory
     * method looks up the cache before calling the {@link
     * Control#newBundle(String, Locale, String, ClassLoader, boolean)
     * control.newBundle} method.  If the time-to-live period of the
     * resource bundle found in the cache has expired, the factory method
     * calls the {@link ResourceBundle.Control#needsReload(String, Locale,
     * String, ClassLoader, ResourceBundle, long) control.needsReload}
     * method to determine whether the resource bundle needs to be reloaded.
     * If reloading is required, the factory method calls
     * <code>control.newBundle</code> to reload the resource bundle.  If
     * <code>control.newBundle</code> returns <code>null</code>, 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 <code>control</code>.
     *
     * <p>All resource bundles loaded are cached by default. Refer to
     * {@link Control#getTimeToLive(String,Locale)
     * control.getTimeToLive} for details.
     *
     *
     * <p>The following is an example of the bundle loading process with the
     * default <code>ResourceBundle.Control</code> implementation.
     * 
     * <p>Conditions:
     * <ul>
     * <li>Base bundle name: <code>foo.bar.Messages</code>
     * <li>Requested <code>Locale</code>: {@link Locale#ITALY}</li>
     * <li>Default <code>Locale</code>: {@link Locale#FRENCH}</li>
     * <li>Available resource bundles:
     * <code>foo/bar/Messages_fr.properties</code> and
     * <code>foo/bar/Messages.properties</code></li>
     *
     * </ul>
     *
     * <p>First, <code>getBundle</code> tries loading a resource bundle in
     * the following sequence.
     *
     * <ul>
     * <li>class <code>foo.bar.Messages_it_IT</code>
     * <li>file <code>foo/bar/Messages_it_IT.properties</code>
     * <li>class <code>foo.bar.Messages_it</code></li>
     * <li>file <code>foo/bar/Messages_it.properties</code></li>
     * <li>class <code>foo.bar.Messages</code></li>
     * <li>file <code>foo/bar/Messages.properties</code></li>
     * </ul>
     *
     * <p>At this point, <code>getBundle</code> finds
     * <code>foo/bar/Messages.properties</code>, which is put on hold
     * because it's the base bundle.  <code>getBundle</code> calls {@link
     * Control#getFallbackLocale(String, Locale)
     * control.getFallbackLocale("foo.bar.Messages", Locale.ITALY)} which
     * returns <code>Locale.FRENCH</code>. Next, <code>getBundle</code>
     * tries loading a bundle in the following sequence.
     *
     * <ul>
     * <li>class <code>foo.bar.Messages_fr</code></li>
     * <li>file <code>foo/bar/Messages_fr.properties</code></li>
     * <li>class <code>foo.bar.Messages</code></li>
     * <li>file <code>foo/bar/Messages.properties</code></li>
     * </ul>
     *
     * <p><code>getBundle</code> finds
     * <code>foo/bar/Messages_fr.properties</code> and creates a
     * <code>ResourceBundle</code> instance. Then, <code>getBundle</code>
     * sets up its parent chain from the list of the candiate locales.  Only
     * <code>foo/bar/Messages.properties</code> is found in the list and
     * <code>getBundle</code> creates a <code>ResourceBundle</code> instance
     * that becomes the parent of the instance for
     * <code>foo/bar/Messages_fr.properties</code>.
     *
     * @param baseName
     *        the base name of the resource bundle, a fully qualified
     *        class name
     * @param targetLocale
     *        the locale for which a resource bundle is desired
     * @param loader
     *        the class loader from which to load the resource bundle
     * @param control
     *        the control which gives information for the resource
     *        bundle loading process
     * @return a resource bundle for the given base name and locale
     * @exception NullPointerException
     *        if <code>baseName</code>, <code>targetLocale</code>,
     *        <code>loader</code>, or <code>control</code> is
     *        <code>null</code>
     * @exception MissingResourceException
     *        if no resource bundle for the specified base name can be found
     * @exception IllegalArgumentException
     *        if the given <code>control</code> doesn't perform properly
     *        (e.g., <code>control.getCandidateLocales</code> returns null.) 
     *        Note that validation of <code>control</code> is performed as
     *        needed.
     * @since 1.6
     */
    public static ResourceBundle getBundle(String baseName, Locale targetLocale,
					   ClassLoader loader, Control control) {
        if (loader == null || control == null) {
            throw new NullPointerException();
        }
        return getBundleImpl(baseName, targetLocale, loader, control);
    }

    private static ResourceBundle getBundleImpl(String baseName, Locale locale,
						ClassLoader loader, Control control) {
	if (locale == null || control == null) {
	    throw new NullPointerException();
	}

	// We create a CacheKey here for use by this call. The base
	// name and loader will never change during the bundle loading
	// process. We have to make sure that the locale is set before
	// using it as a cache key.
	CacheKey cacheKey = new CacheKey(baseName, locale, loader);
	ResourceBundle bundle = null;

	// Quick lookup of the cache.
	BundleReference bundleRef = cacheList.get(cacheKey);
	if (bundleRef != null) {
	    bundle = bundleRef.get();
	    bundleRef = null;
	}

	// If this bundle and all of its parents are valid (not expired),
	// then return this bundle. If any of the bundles is expired, we
	// don't call control.needsReload here but instead drop into the
	// complete loading process below.
	if (isValidBundle(bundle) && hasValidParentChain(bundle)) {
	    return bundle;
	}

        // No valid bundle was found in the cache, so we need to load the
        // resource bundle and its parents.

	boolean isKnownControl = (control == Control.INSTANCE) ||
				   (control instanceof SingleFormatControl);
	List<String> formats = control.getFormats(baseName);
	if (!isKnownControl && !checkList(formats)) {
	    throw new IllegalArgumentException("Invalid Control: getFormats");
	}

	ResourceBundle baseBundle = null;
	for (Locale targetLocale = locale;
	     targetLocale != null;
	     targetLocale = control.getFallbackLocale(baseName, targetLocale)) {
	    List<Locale> candidateLocales = control.getCandidateLocales(baseName, targetLocale);
	    if (!isKnownControl && !checkList(candidateLocales)) {
		throw new IllegalArgumentException("Invalid Control: getCandidateLocales");
	    }

	    bundle = findBundle(cacheKey, candidateLocales, formats, 0, control, baseBundle);

	    // If the loaded bundle is the base bundle and exactly for the
	    // requested locale or the only candidate locale, then take the
	    // bundle as the resulting one. If the loaded bundle is the base
	    // bundle, it's put on hold until we finish processing all
	    // fallback locales.
	    if (isValidBundle(bundle)) {
		boolean isBaseBundle = Locale.ROOT.equals(bundle.locale);
		if (!isBaseBundle || bundle.locale.equals(locale)
		    || (candidateLocales.size() == 1
			&& bundle.locale.equals(candidateLocales.get(0)))) {
		    break;
		}

		// If the base bundle has been loaded, keep the reference in
		// baseBundle so that we can avoid any redundant loading in case
		// the control specify not to cache bundles.
		if (isBaseBundle && baseBundle == null) {
		    baseBundle = bundle;
		}
	    }
	}

	if (bundle == null) {
	    if (baseBundle == null) {
		throwMissingResourceException(baseName, locale, cacheKey.getCause());
	    }
	    bundle = baseBundle;
	}

	return bundle;
    }

    /**
     * Checks if the given <code>List</code> is not null, not empty,
     * not having null in its elements.
     */
    private static final boolean checkList(List a) {
	boolean valid = (a != null && a.size() != 0);
	if (valid) {
	    int size = a.size();
	    for (int i = 0; valid && i < size; i++) {
		valid = (a.get(i) != null);
	    }
	}
	return valid;
    }

    private static final ResourceBundle findBundle(CacheKey cacheKey,
						   List<Locale> candidateLocales,
						   List<String> formats,
						   int index,
						   Control control,
						   ResourceBundle baseBundle) {
	Locale targetLocale = candidateLocales.get(index);
	ResourceBundle parent = null;
	if (index != candidateLocales.size() - 1) {
	    parent = findBundle(cacheKey, candidateLocales, formats, index + 1,
				control, baseBundle);
	} else if (baseBundle != null && Locale.ROOT.equals(targetLocale)) {
	    return baseBundle;
	}

	// Before we do the real loading work, see whether we need to
	// do some housekeeping: If references to class loaders or
	// resource bundles have been nulled out, remove all related
	// information from the cache.
	Object ref;
	while ((ref = referenceQueue.poll()) != null) {
	    cacheList.remove(((CacheKeyReference)ref).getCacheKey());
	}

	// flag indicating the resource bundle has expired in the cache
	boolean expiredBundle = false;

	// First, look up the cache to see if it's in the cache, without
	// declaring beginLoading.
	cacheKey.setLocale(targetLocale);
	ResourceBundle bundle = findBundleInCache(cacheKey, control);
	if (isValidBundle(bundle)) {
	    expiredBundle = bundle.expired;
	    if (!expiredBundle) {
		// If its parent is the one asked for by the candidate
		// locales (the runtime lookup path), we can take the cached
		// one. (If it's not identical, then we'd have to check the
		// parent's parents to be consistent with what's been
		// requested.)
		if (bundle.parent == parent) {
		    return bundle;
		}
		// Otherwise, remove the cached one since we can't keep
		// the same bundles having different parents.
		BundleReference bundleRef = cacheList.get(cacheKey);
		if (bundleRef != null && bundleRef.get() == bundle) {
		    cacheList.remove(cacheKey, bundleRef);
		}
	    }
	}

	if (bundle != NONEXISTENT_BUNDLE) {
	    CacheKey constKey = (CacheKey) cacheKey.clone();

	    // Try declaring loading. If beginLoading() returns true,
	    // then we can proceed. Otherwise, we need to take a look
	    // at the cache again to see if someone else has loaded
	    // the bundle and put it in the cache while we've been
	    // waiting for other loading work to complete.
	    while (!beginLoading(constKey)) {
		bundle = findBundleInCache(cacheKey, control);
		if (bundle == null) {
		    continue;
		}
		if (bundle == NONEXISTENT_BUNDLE) {
		    // If the bundle is NONEXISTENT_BUNDLE, the bundle doesn't exist.
		    return parent;
		}
		expiredBundle = bundle.expired;
		if (!expiredBundle) {
		    if (bundle.parent == parent) {
			return bundle;
		    }
		    BundleReference bundleRef = cacheList.get(cacheKey);
		    if (bundleRef != null && bundleRef.get() == bundle) {
			cacheList.remove(cacheKey, bundleRef);
		    }
		}
	    }
		    
	    bundle = loadBundle(cacheKey, formats, control, expiredBundle);
	    if (bundle != null) {
		if (bundle.parent == null) {
		    bundle.setParent(parent);
		}
		bundle.locale = targetLocale;	
		bundle = putBundleInCache(cacheKey, bundle, control);
		endLoading(constKey);
		return bundle;
	    }

	    // Put NONEXISTENT_BUNDLE in the cache as a mark that there's no bundle
	    // instance for the locale.
	    putBundleInCache(cacheKey, NONEXISTENT_BUNDLE, control);
	    endLoading(constKey);
	}
	assert underConstruction.get(cacheKey) != Thread.currentThread();
	return parent;
    }

    private static final ResourceBundle loadBundle(CacheKey cacheKey,
						   List<String> formats,
						   Control control,
						   boolean reload) {
	assert underConstruction.get(cacheKey) == Thread.currentThread();

	// Here we actually load the bundle in the order of formats
	// specified by the getFormats() value.
	Locale targetLocale = cacheKey.getLocale();

	ResourceBundle bundle = null;
	int size = formats.size();
	for (int i = 0; i < size; i++) {
	    String format = formats.get(i);
	    try {
		bundle = control.newBundle(cacheKey.getName(), targetLocale, format,
					   cacheKey.getLoader(), reload);
	    } catch (Throwable cause) {
		cacheKey.setCause(cause);
	    }
	    if (bundle != null) {
		// Set the format in the cache key so that it can be
		// used when calling needsReload later.
		cacheKey.setFormat(format);
		bundle.name = cacheKey.getName();
		bundle.locale = targetLocale;
		// Bundle provider might reuse instances. So we should make
		// sure to clear the expired flag here.
		bundle.expired = false;
		break;
	    }
	}
	assert underConstruction.get(cacheKey) == Thread.currentThread();

	return bundle;
    }

    private static final boolean isValidBundle(ResourceBundle bundle) {
	return bundle != null && bundle != NONEXISTENT_BUNDLE;
    }

    /**
     * Determines whether any of resource bundles in the parent chain,
     * including the leaf, have expired.
     */
    private static final boolean hasValidParentChain(ResourceBundle bundle) {
	long now = System.currentTimeMillis();
	while (bundle != null) {
	    if (bundle.expired) {
		return false;
	    }
	    CacheKey key = bundle.cacheKey;
	    if (key != null) {
		long expirationTime = key.expirationTime;
		if (expirationTime >= 0 && expirationTime <= now) {
		    return false;
		}
	    }
	    bundle = bundle.parent;
	}
	return true;
    }

    /**
     * Declares the beginning of actual resource bundle loading. This method
     * returns true if the declaration is successful and the current thread has
     * been put in underConstruction. If someone else has already begun
     * loading, this method waits until that loading work is complete and
     * returns false.
     */
    private static final boolean beginLoading(CacheKey constKey) {
	Thread me = Thread.currentThread();
	Thread worker;
	// We need to declare by putting the current Thread (me) to
	// underConstruction that we are working on loading the specified
	// resource bundle. If we are already working the loading, it means
	// that the resource loading requires a recursive call. In that case,
	// we have to proceed. (4300693)
	if (((worker = underConstruction.putIfAbsent(constKey, me)) == null)
	    || worker == me) {
	    return true;
	}

	// If someone else is working on the loading, wait until
	// the Thread finishes the bundle loading.
	synchronized (worker) {
	    while (underConstruction.get(constKey) == worker) {
		try {
		    worker.wait();
		} catch (InterruptedException e) {
		}
	    }
	}
	return false;
    }

    /**
     * Declares the end of the bundle loading. This method calls notifyAll
     * for those who are waiting for this completion.
     */
    private static final void endLoading(CacheKey constKey) {
	// Remove this Thread from the underConstruction map and wake up
	// those who have been waiting for me to complete this bundle
	// loading.
	Thread me = Thread.currentThread();
	assert (underConstruction.get(constKey) == me);
	underConstruction.remove(constKey);
	synchronized (me) {
	    me.notifyAll();
	}
    }

    /**
     * Throw a MissingResourceException with proper message
     */
    private static final void throwMissingResourceException(String baseName,
							    Locale locale,
							    Throwable cause) {
	// If the cause is a MissingResourceException, avoid creating
	// a long chain. (6355009)
	if (cause instanceof MissingResourceException) {
	    cause = null;
	}
        throw new MissingResourceException("Can't find bundle for base name "
                                           + baseName + ", locale " + locale,
                                           baseName + "_" + locale, // className
					   "",                      // key
					   cause);
    }

    /**
     * Finds a bundle in the cache. Any expired bundles are marked as
     * `expired' and removed from the cache upon return.
     *
     * @param cacheKey the key to look up the cache
     * @param control the Control to be used for the expiration control
     * @return the cached bundle, or null if the bundle is not found in the
     * cache or its parent has expired. <code>bundle.expire</code> is true
     * upon return if the bundle in the cache has expired.
     */
    private static final ResourceBundle findBundleInCache(CacheKey cacheKey,
							  Control control) {
	BundleReference bundleRef = cacheList.get(cacheKey);
	if (bundleRef == null) {
	    return null;
	}
	ResourceBundle bundle = bundleRef.get();
	if (bundle == null) {
	    return null;
	}
	ResourceBundle p = bundle.parent;
	assert p != NONEXISTENT_BUNDLE;
	// If the parent has expired, then this one must also expire. We
	// check only the immediate parent because the actual loading is
	// done from the root (base) to leaf (child) and the purpose of
	// checking is to propagate expiration towards the leaf. For
	// example, if the requested locale is ja_JP_JP and there are
	// bundles for all of the candidates in the cache, we have a list,
	//
	// base <- ja <- ja_JP <- ja_JP_JP
	//
	// If ja has expired, then it will reload ja and the list becomes a
	// tree.
	//
	// base <- ja (new)
	//  "   <- ja (expired) <- ja_JP <- ja_JP_JP
	//
	// When looking up ja_JP in the cache, it finds ja_JP in the cache
	// which references to the expired ja. Then, ja_JP is marked as
	// expired and removed from the cache. This will be propagated to
	// ja_JP_JP.
	//
	// Now, it's possible, for example, that while loading new ja_JP,
	// someone else has started loading the same bundle and finds the
	// base bundle has expired. Then, what we get from the first
	// getBundle call includes the expired base bundle. However, if
	// someone else didn't start its loading, we wouldn't know if the
	// base bundle has expired at the end of the loading process. The
	// expiration control doesn't guarantee that the returned bundle and
	// its parents haven't expired.
	//
	// We could check the entire parent chain to see if there's any in
	// the chain that has expired. But this process may never end. An
	// extreme case would be that getTimeToLive returns 0 and
	// needsReload always returns true.
	if (p != null && p.expired) {
	    assert bundle != NONEXISTENT_BUNDLE;
	    bundle.expired = true;
	    bundle.cacheKey = null;
	    cacheList.remove(cacheKey, bundleRef);
	    bundle = null;
	} else {
	    CacheKey key = bundleRef.getCacheKey();
	    long expirationTime = key.expirationTime;
	    if (!bundle.expired && expirationTime >= 0 &&
		expirationTime <= System.currentTimeMillis()) {
		// its TTL period has expired.
		if (bundle != NONEXISTENT_BUNDLE) {
		    // Synchronize here to call needsReload to avoid
		    // redundant concurrent calls for the same bundle.
		    synchronized (bundle) {
			expirationTime = key.expirationTime;
			if (!bundle.expired && expirationTime >= 0 &&
			    expirationTime <= System.currentTimeMillis()) {
			    try {
				bundle.expired = control.needsReload(key.getName(),
								     key.getLocale(),
								     key.getFormat(),
								     key.getLoader(),
								     bundle,
								     key.loadTime);
			    } catch (Exception e) {
				cacheKey.setCause(e);
			    }
			    if (bundle.expired) {
				// If the bundle needs to be reloaded, then
				// remove the bundle from the cache, but
				// return the bundle with the expired flag
				// on.
				bundle.cacheKey = null;
				cacheList.remove(cacheKey, bundleRef);
			    } else {
				// Update the expiration control info. and reuse
				// the same bundle instance
				setExpirationTime(key, control);
			    }
			}
		    }
		} else {
		    // We just remove NONEXISTENT_BUNDLE from the cache.
		    cacheList.remove(cacheKey, bundleRef);
		    bundle = null;
		}
	    }
	}
	return bundle;
    }

    /**
     * Put a new bundle in the cache.
     *
     * @param cacheKey the key for the resource bundle
     * @param bundle the resource bundle to be put in the cache
     * @return the ResourceBundle for the cacheKey; if someone has put
     * the bundle before this call, the one found in the cache is
     * returned.
     */
    private static final ResourceBundle putBundleInCache(CacheKey cacheKey,
							 ResourceBundle bundle,
							 Control control) {
	setExpirationTime(cacheKey, control);
	if (cacheKey.expirationTime != Control.TTL_DONT_CACHE) {
	    CacheKey key = (CacheKey) cacheKey.clone();
	    BundleReference bundleRef = new BundleReference(bundle, referenceQueue, key);
	    bundle.cacheKey = key;

	    // Put the bundle in the cache if it's not been in the cache.
	    BundleReference result = cacheList.putIfAbsent(key, bundleRef);

	    // If someone else has put the same bundle in the cache before
	    // us and it has not expired, we should use the one in the cache.
	    if (result != null) {
		ResourceBundle rb = result.get();
		if (rb != null && !rb.expired) {
		    // Clear the back link to the cache key
		    bundle.cacheKey = null;
		    bundle = rb;
		    // Clear the reference in the BundleReference so that
		    // it won't be enqueued.
		    bundleRef.clear();
		} else {
		    // Replace the invalid (garbage collected or expired)
		    // instance with the valid one.
		    cacheList.put(key, bundleRef);
		}
	    }
	}
	return bundle;
    }

    private static final void setExpirationTime(CacheKey cacheKey, Control control) {
	long ttl = control.getTimeToLive(cacheKey.getName(),
					 cacheKey.getLocale());
	if (ttl >= 0) {
	    // If any expiration time is specified, set the time to be
	    // expired in the cache.
	    long now = System.currentTimeMillis();
	    cacheKey.loadTime = now;
	    cacheKey.expirationTime = now + ttl;
	} else if (ttl >= Control.TTL_NO_EXPIRATION_CONTROL) {
	    cacheKey.expirationTime = ttl;
	} else {
	    throw new IllegalArgumentException("Invalid Control: TTL=" + ttl);
	}
    }

    /**
     * Removes all resource bundles from the cache that have been loaded
     * using the caller's class loader.
     *
     * @since 1.6
     * @see ResourceBundle.Control#getTimeToLive(String,Locale)
     */
    public static final void clearCache() {
	clearCache(getLoader());
    }

    /**
     * Removes all resource bundles from the cache that have been loaded
     * using the given class loader.
     *
     * @param loader the class loader
     * @exception NullPointerException if <code>loader</code> is null
     * @since 1.6
     * @see ResourceBundle.Control#getTimeToLive(String,Locale)
     */
    public static final void clearCache(ClassLoader loader) {
	if (loader == null) {
	    throw new NullPointerException();
	}
	Set<CacheKey> set = cacheList.keySet();
	for (CacheKey key : set) {
	    if (key.getLoader() == loader) {
		set.remove(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.
     *
     * @param key the key for the desired object
     * @exception NullPointerException if <code>key</code> is <code>null</code>
     * @return the object for the given key, or null
     */
    protected abstract Object handleGetObject(String key);

    /**
     * Returns an enumeration of the keys.
     *
     * @return an <code>Enumeration</code> of the keys contained in
     *         this <code>ResourceBundle</code> and its parent bundles.
     */
    public abstract Enumeration<String> getKeys();

    /**
     * Determines whether the given <code>key</code> is contained in
     * this <code>ResourceBundle</code> or its parent bundles.
     *
     * @param key
     *        the resource <code>key</code>
     * @return <code>true</code> if the given <code>key</code> is
     *        contained in this <code>ResourceBundle</code> or its
     *        parent bundles; <code>false</code> otherwise.
     * @exception NullPointerException
     *         if <code>key</code> is <code>null</code>
     * @since 1.6
     */
    public boolean containsKey(String key) {
	if (key == null) {
	    throw new NullPointerException();
	}
	for (ResourceBundle rb = this; rb != null; rb = rb.parent) {
	    if (rb.handleKeySet().contains(key)) {
		return true;
	    }
	}
	return false;
    }

    /**
     * Returns a <code>Set</code> of all keys contained in this
     * <code>ResourceBundle</code> and its parent bundles.
     *
     * @return a <code>Set</code> of all keys contained in this
     *         <code>ResourceBundle</code> and its parent bundles.
     * @since 1.6
     */
    public Set<String> keySet() {
	Set<String> keys = new HashSet<String>();
	for (ResourceBundle rb = this; rb != null; rb = rb.parent) {
	    keys.addAll(rb.handleKeySet());
	}
	return keys;
    }

    /**
     * Returns a <code>Set</code> of the keys contained <em>only</em>
     * in this <code>ResourceBundle</code>.
     *
     * <p>The default implementation returns a <code>Set</code> of the
     * keys returned by the {@link #getKeys() getKeys} method except
     * for the ones for which the {@link #handleGetObject(String)
     * handleGetObject} method returns <code>null</code>. Once the
     * <code>Set</code> has been created, the value is kept in this
     * <code>ResourceBundle</code> in order to avoid producing the
     * same <code>Set</code> in the next calls.  Override this method
     * in subclass implementations for faster handling.
     *
     * @return a <code>Set</code> of the keys contained only in this
     *        <code>ResourceBundle</code>
     * @since 1.6
     */
    protected Set<String> handleKeySet() {
	if (keySet == null) {
	    synchronized (this) {
		if (keySet == null) {
		    Set<String> keys = new HashSet<String>();
		    Enumeration<String> enumKeys = getKeys();
		    while (enumKeys.hasMoreElements()) {
			String key = enumKeys.nextElement();
			if (handleGetObject(key) != null) {
			    keys.add(key);
			}
		    }
		    keySet = keys;
		}
	    }
	}
	return keySet;
    }



    /**
     * <code>ResourceBundle.Control</code> defines a set of callback methods
     * that are invoked by the {@link ResourceBundle#getBundle(String,
     * Locale, ClassLoader, Control) ResourceBundle.getBundle} factory
     * methods during the bundle loading process. In other words, a
     * <code>ResourceBundle.Control</code> collaborates with the factory
     * methods for loading resource bundles. The default implementation of
     * the callback methods provides the information necessary for the
     * factory methods to perform the <a
     * href="./ResourceBundle.html#default_behavior">default behavior</a>.
     *
     * <p>In addition to the callback methods, the {@link
     * #toBundleName(String, Locale) toBundleName} and {@link
     * #toResourceName(String, String) toResourceName} methods are defined
     * primarily for convenience in implementing the callback
     * methods. However, the <code>toBundleName</code> method could be
     * overridden to provide different conventions in the organization and
     * packaging of localized resources.  The <code>toResourceName</code>
     * method is <code>final</code> to avoid use of wrong resource and class
     * name separators.
     *
     * <p>Two factory methods, {@link #getControl(List)} and {@link
     * #getNoFallbackControl(List)}, provide
     * <code>ResourceBundle.Control</code> instances that implement common
     * variations of the default bundle loading process.
     *
     * <p>The formats returned by the {@link Control#getFormats(String)
     * getFormats} method and candidate locales returned by the {@link
     * ResourceBundle.Control#getCandidateLocales(String, Locale)
     * getCandidateLocales} method must be consistent in all
     * <code>ResourceBundle.getBundle</code> invocations for the same base
     * bundle. Otherwise, the <code>ResourceBundle.getBundle</code> methods
     * may return unintended bundles. For example, if only
     * <code>"java.class"</code> is returned by the <code>getFormats</code>
     * method for the first call to <code>ResourceBundle.getBundle</code>
     * and only <code>"java.properties"</code> for the second call, then the
     * second call will return the class-based one that has been cached
     * during the first call.
     *
     * <p>A <code>ResourceBundle.Control</code> instance must be thread-safe
     * if it's simultaneously used by multiple threads.
     * <code>ResourceBundle.getBundle</code> does not synchronize to call
     * the <code>ResourceBundle.Control</code> methods. The default
     * implementations of the methods are thread-safe.
     *
     * <p>Applications can specify <code>ResourceBundle.Control</code>
     * instances returned by the <code>getControl</code> factory methods or
     * created from a subclass of <code>ResourceBundle.Control</code> to
     * customize the bundle loading process. The following are examples of
     * changing the default bundle loading process.
     *
     * <p><b>Example 1</b>
     *
     * <p>The following code lets <code>ResourceBundle.getBundle</code> look
     * up only properties-based resources.
     *
     * <pre>
     * import java.util.*;
     * import static java.util.ResourceBundle.Control.*;
     * ...
     * ResourceBundle bundle =
     *   ResourceBundle.getBundle("MyResources", new Locale("fr", "CH"),
     *                            ResourceBundle.Control.getControl(FORMAT_PROPERTIES));
     * </pre>
     *
     * Given the resource bundles in the <a
     * href="./ResourceBundle.html#default_behavior_example">example</a> in
     * the <code>ResourceBundle.getBundle</code> description, this
     * <code>ResourceBundle.getBundle</code> call loads
     * <code>MyResources_fr_CH.properties</code> whose parent is
     * <code>MyResources_fr.properties</code> whose parent is
     * <code>MyResources.properties</code>. (<code>MyResources_fr_CH.properties</code>
     * is not hidden, but <code>MyResources_fr_CH.class</code> is.)
     *
     * <p><b>Example 2</b>
     *
     * <p>The following is an example of loading XML-based bundles
     * using {@link Properties#loadFromXML(java.io.InputStream)
     * Properties.loadFromXML}.
     *
     * <pre>
     * ResourceBundle rb = ResourceBundle.getBundle("Messages",
     *     new ResourceBundle.Control() {
     *         public List&lt;String&gt; getFormats(String baseName) {
     *             if (baseName == null)
     *                 throw new NullPointerException();
     *             return Arrays.asList("xml");
     *         }
     *         public ResourceBundle newBundle(String baseName,
     *                                         Locale locale,
     *                                         String format,
     *                                         ClassLoader loader,
     *                                         boolean reload)
     *                          throws IllegalAccessException,
     *                                 InstantiationException,
     *                                 IOException {
     *             if (baseName == null || locale == null
     *                   || format == null || loader == null)
     *                 throw new NullPointerException();
     *             ResourceBundle bundle = null;
     *             if (format.equals("xml")) {
     *                 String bundleName = toBundleName(baseName, locale);
     *                 String resourceName = toResourceName(bundleName, format);
     *                 InputStream stream = null;
     *                 if (reload) {
     *                     URL url = loader.getResource(resourceName);
     *                     if (url != null) {
     *                         URLConnection connection = url.openConnection();
     *                         if (connection != null) {
     *                             // Disable caches to get fresh data for
     *                             // reloading.
     *                             connection.setUseCaches(false);
     *                             stream = connection.getInputStream();
     *                         }
     *                     }
     *                 } else {
     *                     stream = loader.getResourceAsStream(resourceName);
     *                 }
     *                 if (stream != null) {
     *                     BufferedInputStream bis = new BufferedInputStream(stream);
     *                     bundle = new XMLResourceBundle(bis);
     *                     bis.close();
     *                 }
     *             }
     *             return bundle;
     *         }
     *     });
     *
     * ...
     *
     * private static class XMLResourceBundle extends ResourceBundle {
     *     private Properties props;
     *     XMLResourceBundle(InputStream stream) throws IOException {
     *         props = new Properties();
     *         props.loadFromXML(stream);
     *     }
     *     protected Object handleGetObject(String key) {
     *         return props.getProperty(key);
     *     }
     *     public Enumeration&lt;String&gt; getKeys() {
     *         ...
     *     }
     * }
     * </pre>
     * 
     * @since 1.6
     */
    public static class Control {
	/**
	 * The default format <code>List</code>, which contains the strings
	 * <code>"java.class"</code> and <code>"java.properties"</code>, in
	 * this order. This <code>List</code> is {@linkplain
	 * Collections#unmodifiableList(List) unmodifiable}.
	 *
	 * @see #getFormats(String)
	 */
	public static final List<String> FORMAT_DEFAULT
	    = Collections.unmodifiableList(Arrays.asList("java.class",
							 "java.properties"));

	/**
	 * The class-only format <code>List</code> containing
	 * <code>"java.class"</code>. This <code>List</code> is {@linkplain
	 * Collections#unmodifiableList(List) unmodifiable}.
	 *
	 * @see #getFormats(String)
	 */
	public static final List<String> FORMAT_CLASS
	    = Collections.unmodifiableList(Arrays.asList("java.class"));

	/**
	 * The properties-only format <code>List</code> containing
	 * <code>"java.properties"</code>. This <code>List</code> is
	 * {@linkplain Collections#unmodifiableList(List) unmodifiable}.
	 *
	 * @see #getFormats(String)
	 */
	public static final List<String> FORMAT_PROPERTIES
	    = Collections.unmodifiableList(Arrays.asList("java.properties"));

	/**
	 * The time-to-live constant for not caching loaded resource bundle
	 * instances.
	 *
	 * @see #getTimeToLive(String, Locale)
	 */
	public static final long TTL_DONT_CACHE = -1;

	/**
	 * The time-to-live constant for disabling the expiration control
	 * for loaded resource bundle instances in the cache.
	 *
	 * @see #getTimeToLive(String, Locale)
	 */
	public static final long TTL_NO_EXPIRATION_CONTROL = -2;

	private static final Control INSTANCE = new Control();

	/**
	 * Sole constructor. (For invocation by subclass constructors,
	 * typically implicit.)
	 */
	protected Control() {
	}

	/**
	 * Returns a <code>ResourceBundle.Control</code> in which the {@link
	 * #getFormats(String) getFormats} method returns the specified
	 * <code>formats</code>. The <code>formats</code> must be equal to
	 * one of {@link Control#FORMAT_PROPERTIES}, {@link
	 * Control#FORMAT_CLASS} or {@link
	 * Control#FORMAT_DEFAULT}. <code>ResourceBundle.Control</code>
	 * instances returned by this method are singletons and thread-safe.
	 *
	 * <p>Specifying {@link Control#FORMAT_DEFAULT} is equivalent to
	 * instantiating the <code>ResourceBundle.Control</code> class,
	 * except that this method returns a singleton.
	 *
	 * @param formats
	 *        the formats to be returned by the
	 *        <code>ResourceBundle.Control.getFormats</code> method
	 * @return a <code>ResourceBundle.Control</code> supporting the
	 *        specified <code>formats</code>
	 * @exception NullPointerException
	 *        if <code>formats</code> is <code>null</code>
	 * @exception IllegalArgumentException
	 *        if <code>formats</code> is unknown
	 */
	public static final Control getControl(List<String> formats) {
	    if (formats.equals(Control.FORMAT_PROPERTIES)) {
		return SingleFormatControl.PROPERTIES_ONLY;
	    }
	    if (formats.equals(Control.FORMAT_CLASS)) {
		return SingleFormatControl.CLASS_ONLY;
	    }
	    if (formats.equals(Control.FORMAT_DEFAULT)) {
		return Control.INSTANCE;
	    }
	    throw new IllegalArgumentException();
	}

	/**
	 * Returns a <code>ResourceBundle.Control</code> in which the {@link
	 * #getFormats(String) getFormats} method returns the specified
	 * <code>formats</code> and the {@link
	 * Control#getFallbackLocale(String, Locale) getFallbackLocale}
	 * method returns <code>null</code>. The <code>formats</code> must
	 * be equal to one of {@link Control#FORMAT_PROPERTIES}, {@link
	 * Control#FORMAT_CLASS} or {@link Control#FORMAT_DEFAULT}.
	 * <code>ResourceBundle.Control</code> instances returned by this
	 * method are singletons and thread-safe.
	 *
	 * @param formats
	 *        the formats to be returned by the
	 *        <code>ResourceBundle.Control.getFormats</code> method
	 * @return a <code>ResourceBundle.Control</code> supporting the
	 *        specified <code>formats</code> with no fallback
	 *        <code>Locale</code> support
	 * @exception NullPointerException
	 *        if <code>formats</code> is <code>null</code>
	 * @exception IllegalArgumentException
	 *        if <code>formats</code> is unknown
	 */
	public static final Control getNoFallbackControl(List<String> formats) {
	    if (formats.equals(Control.FORMAT_DEFAULT)) {
		return NoFallbackControl.NO_FALLBACK;
	    }
	    if (formats.equals(Control.FORMAT_PROPERTIES)) {
		return NoFallbackControl.PROPERTIES_ONLY_NO_FALLBACK;
	    }
	    if (formats.equals(Control.FORMAT_CLASS)) {
		return NoFallbackControl.CLASS_ONLY_NO_FALLBACK;
	    }
	    throw new IllegalArgumentException();
	}

	/**
	 * Returns a <code>List</code> of <code>String</code>s containing
	 * formats to be used to load resource bundles for the given
	 * <code>baseName</code>. The <code>ResourceBundle.getBundle</code>
	 * factory method tries to load resource bundles with formats in the
	 * order specified by the list. The list returned by this method
	 * must have at least one <code>String</code>. The predefined
	 * formats are <code>"java.class"</code> for class-based resource
	 * bundles and <code>"java.properties"</code> for {@linkplain
	 * PropertyResourceBundle properties-based} ones. Strings starting
	 * with <code>"java."</code> are reserved for future extensions and
	 * must not be used by application-defined formats.
	 *
	 * <p>It is not a requirement to return an immutable (unmodifiable)
	 * <code>List</code>.  However, the returned <code>List</code> must
	 * not be mutated after it has been returned by
	 * <code>getFormats</code>.
	 *
	 * <p>The default implementation returns {@link #FORMAT_DEFAULT} so
	 * that the <code>ResourceBundle.getBundle</code> factory method
	 * looks up first class-based resource bundles, then
	 * properties-based ones.
	 *
         * @param baseName
	 *        the base name of the resource bundle, a fully qualified class
	 *        name
	 * @return a <code>List</code> of <code>String</code>s containing
	 *        formats for loading resource bundles.
	 * @exception NullPointerException
	 *        if <code>baseName</code> is null
	 * @see #FORMAT_DEFAULT
	 * @see #FORMAT_CLASS
	 * @see #FORMAT_PROPERTIES
	 */
	public List<String> getFormats(String baseName) {
	    if (baseName == null) {
		throw new NullPointerException();
	    }
	    return FORMAT_DEFAULT;
	}

	/**
	 * Returns a <code>List</code> of <code>Locale</code>s as candidate
	 * locales for <code>baseName</code> and <code>locale</code>. This
	 * method is called by the <code>ResourceBundle.getBundle</code>
	 * factory method each time the factory method tries finding a
	 * resource bundle for a target <code>Locale</code>.
	 *
	 * <p>The sequence of the candidate locales also corresponds to the
	 * runtime resource lookup path (also known as the <I>parent
	 * chain</I>), if the corresponding resource bundles for the
	 * candidate locales exist and their parents are not defined by
	 * loaded resource bundles themselves.  The last element of the list
	 * must be a {@linkplain Locale#ROOT root locale} if it is desired to 
	 * have the base bundle as the terminal of the parent chain.
	 *
	 * <p>If the given locale is equal to <code>Locale.ROOT</code> (the
	 * root locale), a <code>List</code> containing only the root
	 * <code>Locale</code> must be returned. In this case, the
	 * <code>ResourceBundle.getBundle</code> factory method loads only
	 * the base bundle as the resulting resource bundle.
	 *
	 * <p>It is not a requirement to return an immutable
	 * (unmodifiable) <code>List</code>. However, the returned
	 * <code>List</code> must not be mutated after it has been
	 * returned by <code>getCandidateLocales</code>.
	 *
	 * <p>The default implementation returns a <code>List</code> containing
	 * <code>Locale</code>s in the following sequence:
	 * <pre>
	 *     Locale(language, country, variant)
	 *     Locale(language, country)
	 *     Locale(language)
	 *     Locale.ROOT
	 * </pre>
	 * where <code>language</code>, <code>country</code> and
	 * <code>variant</code> are the language, country and variant values
	 * of the given <code>locale</code>, respectively. Locales where the
	 * final component values are empty strings are omitted.
	 *
	 * <p>The default implementation uses an {@link ArrayList} that
	 * overriding implementations may modify before returning it to the
	 * caller. However, a subclass must not modify it after it has
	 * been returned by <code>getCandidateLocales</code>.
	 *
	 * <p>For example, if the given <code>baseName</code> is "Messages"
	 * and the given <code>locale</code> is
	 * <code>Locale("ja",&nbsp;"",&nbsp;"XX")</code>, then a
	 * <code>List</code> of <code>Locale</code>s:
	 * <pre>
	 *     Locale("ja", "", "XX")
	 *     Locale("ja")
	 *     Locale.ROOT
	 * </pre>
	 * is returned. And if the resource bundles for the "ja" and
	 * "" <code>Locale</code>s are found, then the runtime resource
	 * lookup path (parent chain) is:
	 * <pre>
	 *     Messages_ja -> Messages
	 * </pre>
	 *
         * @param baseName
	 *        the base name of the resource bundle, a fully
	 *        qualified class name
	 * @param locale
	 *        the locale for which a resource bundle is desired
	 * @return a <code>List</code> of candidate
	 *        <code>Locale</code>s for the given <code>locale</code>
         * @exception NullPointerException
         *        if <code>baseName</code> or <code>locale</code> is
         *        <code>null</code>
	 */
	public List<Locale> getCandidateLocales(String baseName, Locale locale) {
	    if (baseName == null) {
		throw new NullPointerException();
	    }
	    String language = locale.getLanguage();
	    String country = locale.getCountry();
	    String variant = locale.getVariant();

	    List<Locale> locales = new ArrayList<Locale>(4);
	    if (variant.length() > 0) {
		locales.add(locale);
	    }
	    if (country.length() > 0) {
		locales.add((locales.size() == 0) ?
			    locale : Locale.getInstance(language, country, ""));
	    }
	    if (language.length() > 0) {
		locales.add((locales.size() == 0) ?
			    locale : Locale.getInstance(language, "", ""));
	    }
	    locales.add(Locale.ROOT);
	    return locales;
	}

	/**
	 * Returns a <code>Locale</code> to be used as a fallback locale for
	 * further resource bundle searches by the
	 * <code>ResourceBundle.getBundle</code> factory method. This method
	 * is called from the factory method every time when no resulting
	 * resource bundle has been found for <code>baseName</code> and
	 * <code>locale</code>, where locale is either the parameter for
	 * <code>ResourceBundle.getBundle</code> or the previous fallback
	 * locale returned by this method.
	 *
	 * <p>The method returns <code>null</code> if no further fallback
	 * search is desired.
	 *
	 * <p>The default implementation returns the {@linkplain
	 * Locale#getDefault() default <code>Locale</code>} if the given
	 * <code>locale</code> isn't the default one.  Otherwise,
	 * <code>null</code> is returned.
	 *
         * @param baseName
	 *        the base name of the resource bundle, a fully
	 *        qualified class name for which
	 *        <code>ResourceBundle.getBundle</code> has been
	 *        unable to find any resource bundles (except for the
	 *        base bundle)
	 * @param locale
	 *        the <code>Locale</code> for which
	 *        <code>ResourceBundle.getBundle</code> has been
	 *        unable to find any resource bundles (except for the
	 *        base bundle)
	 * @return a <code>Locale</code> for the fallback search,
	 *        or <code>null</code> if no further fallback search
	 *        is desired.
         * @exception NullPointerException
         *        if <code>baseName</code> or <code>locale</code>
         *        is <code>null</code>
	 */
	public Locale getFallbackLocale(String baseName, Locale locale) {
	    if (baseName == null) {
		throw new NullPointerException();
	    }
	    Locale defaultLocale = Locale.getDefault();
	    return locale.equals(defaultLocale) ? null : defaultLocale;
	}

        /**
         * Instantiates a resource bundle for the given bundle name of the
         * given format and locale, using the given class loader if
         * necessary. This method returns <code>null</code> if there is no
         * resource bundle available for the given parameters. If a resource
         * bundle can't be instantiated due to an unexpected error, the
         * error must be reported by throwing an <code>Error</code> or
         * <code>Exception</code> rather than simply returning
         * <code>null</code>.
	 *
	 * <p>If the <code>reload</code> flag is <code>true</code>, it
	 * indicates that this method is being called because the previously
	 * loaded resource bundle has expired.
	 *
	 * <p>The default implementation instantiates a
	 * <code>ResourceBundle</code> as follows.
	 *
	 * <ul>
	 *
	 * <li>The bundle name is obtained by calling {@link
	 * #toBundleName(String, Locale) toBundleName(baseName,
	 * locale)}.</li>
	 *
	 * <li>If <code>format</code> is <code>"java.class"</code>, the
	 * {@link Class} specified by the bundle name is loaded by calling
	 * {@link ClassLoader#loadClass(String)}. Then, a
	 * <code>ResourceBundle</code> is instantiated by calling {@link
	 * Class#newInstance()}.  Note that the <code>reload</code> flag is
	 * ignored for loading class-based resource bundles in this default
	 * implementation.</li>
         *
	 * <li>If <code>format</code> is <code>"java.properties"</code>,
	 * {@link #toResourceName(String, String) toResourceName(bundlename,
	 * "properties")} is called to get the resource name.
	 * If <code>reload</code> is <code>true</code>, {@link
	 * ClassLoader#getResource(String) load.getResource} is called
	 * to get a {@link URL} for creating a {@link
	 * URLConnection}. This <code>URLConnection</code> is used to
	 * {@linkplain URLConnection#setUseCaches(boolean) disable the
	 * caches} of the underlying resource loading layers,
	 * and to {@linkplain URLConnection#getInputStream() get an
	 * <code>InputStream</code>}.
	 * Otherwise, {@link ClassLoader#getResourceAsStream(String)
	 * loader.getResourceAsStream} is called to get an {@link
	 * InputStream}. Then, a {@link
	 * PropertyResourceBundle} is constructed with the
	 * <code>InputStream</code>.</li>
	 *
	 * <li>If <code>format</code> is neither <code>"java.class"</code>
	 * nor <code>"java.properties"</code>, an
	 * <code>IllegalArgumentException</code> is thrown.</li>
	 *
	 * </ul>
	 *
         * @param baseName
	 *        the base bundle name of the resource bundle, a fully
	 *        qualified class name
	 * @param locale
	 *        the locale for which the resource bundle should be
	 *        instantiated
         * @param format
	 *        the resource bundle format to be loaded
         * @param loader
	 *        the <code>ClassLoader</code> to use to load the bundle
	 * @param reload
	 *        the flag to indicate bundle reloading; <code>true</code>
	 *        if reloading an expired resource bundle,
	 *        <code>false</code> otherwise
         * @return the resource bundle instance,
	 *        or <code>null</code> if none could be found.
         * @exception NullPointerException
	 *        if <code>bundleName</code>, <code>locale</code>,
	 *        <code>format</code>, or <code>loader</code> is
	 *        <code>null</code>, or if <code>null</code> is returned by
	 *        {@link #toBundleName(String, Locale) toBundleName}
	 * @exception IllegalArgumentException
	 *        if <code>format</code> is unknown, or if the resource
	 *        found for the given parameters contains malformed data.
	 * @exception ClassCastException
	 *        if the loaded class cannot be cast to <code>ResourceBundle</code>
	 * @exception IllegalAccessException
	 *        if the class or its nullary constructor is not
	 *        accessible.
	 * @exception InstantiationException
	 *        if the instantiation of a class fails for some other
	 *        reason.
	 * @exception ExceptionInInitializerError
	 *        if the initialization provoked by this method fails.
	 * @exception SecurityException
	 *        If a security manager is present and creation of new
	 *        instances is denied. See {@link Class#newInstance()}
	 *        for details.
	 * @exception IOException
	 *        if an error occurred when reading resources using
	 *        any I/O operations
         */
	public ResourceBundle newBundle(String baseName, Locale locale, String format,
					ClassLoader loader, boolean reload)
		    throws IllegalAccessException, InstantiationException, IOException {
	    String bundleName = toBundleName(baseName, locale);
	    ResourceBundle bundle = null;
	    if (format.equals("java.class")) {
		try {
		    Class<? extends ResourceBundle> bundleClass
			= (Class<? extends ResourceBundle>)loader.loadClass(bundleName);

		    // If the class isn't a ResourceBundle subclass, throw a
		    // ClassCastException.
		    if (ResourceBundle.class.isAssignableFrom(bundleClass)) {
			bundle = bundleClass.newInstance();
		    } else {
			throw new ClassCastException(bundleClass.getName()
				     + " cannot be cast to ResourceBundle");
		    }
		} catch (ClassNotFoundException e) {
		}
	    } else if (format.equals("java.properties")) {
		final String resourceName = toResourceName(bundleName, "properties");
		final ClassLoader classLoader = loader;
		final boolean reloadFlag = reload;
		InputStream stream = null;
		try {
		    stream = AccessController.doPrivileged(
			new PrivilegedExceptionAction<InputStream>() {
			    public InputStream run() throws IOException {
				InputStream is = null;
				if (reloadFlag) {
				    URL url = classLoader.getResource(resourceName);
				    if (url != null) {
					URLConnection connection = url.openConnection();
					if (connection != null) {
					    // Disable caches to get fresh data for
					    // reloading.
					    connection.setUseCaches(false);
					    is = connection.getInputStream();
					}
				    }
				} else {
				    is = classLoader.getResourceAsStream(resourceName);
				}
				return is;
			    }
			});
		} catch (PrivilegedActionException e) {
		    throw (IOException) e.getException();
		}
		if (stream != null) {
		    try {
			bundle = new PropertyResourceBundle(stream);
		    } finally {
			stream.close();
		    }
		}
	    } else {
		throw new IllegalArgumentException("unknown format: " + format);
	    }
	    return bundle;
	}

	/**
	 * Returns the time-to-live (TTL) value for resource bundles that
	 * are loaded under this
	 * <code>ResourceBundle.Control</code>. Positive time-to-live values
	 * specify the number of milliseconds a bundle can remain in the
	 * cache without being validated against the source data from which
	 * it was constructed. The value 0 indicates that a bundle must be
	 * validated each time it is retrieved from the cache. {@link
	 * #TTL_DONT_CACHE} specifies that loaded resource bundles are not
	 * put in the cache. {@link #TTL_NO_EXPIRATION_CONTROL} specifies
	 * that loaded resource bundles are put in the cache with no
	 * expiration control.
	 *
	 * <p>The expiration affects only the bundle loading process by the
	 * <code>ResourceBundle.getBundle</code> factory method.  That is,
	 * if the factory method finds a resource bundle in the cache that
	 * has expired, the factory method calls the {@link
	 * #needsReload(String, Locale, String, ClassLoader, ResourceBundle,
	 * long) needsReload} method to determine whether the resource
	 * bundle needs to be reloaded. If <code>needsReload</code> returns
	 * <code>true</code>, the cached resource bundle instance is removed
	 * from the cache. Otherwise, the instance stays in the cache,
	 * updated with the new TTL value returned by this method.
	 *
	 * <p>All cached resource bundles are subject to removal from the
	 * cache due to memory constraints of the runtime environment.
	 * Returning a large positive value doesn't mean to lock loaded
	 * resource bundles in the cache.
	 *
	 * <p>The default implementation returns {@link #TTL_NO_EXPIRATION_CONTROL}.
	 *
	 * @param baseName
	 *	  the base name of the resource bundle for which the
	 *	  expiration value is specified.
	 * @param locale
	 *        the locale of the resource bundle for which the
	 *        expiration value is specified.
	 * @return the time (0 or a positive millisecond offset from the
	 *        cached time) to get loaded bundles expired in the cache,
	 *        {@link #TTL_NO_EXPIRATION_CONTROL} to disable the
	 *        expiration control, or {@link #TTL_DONT_CACHE} to disable
	 *        caching.
	 * @exception NullPointerException
	 *	  if <code>baseName</code> or <code>locale</code> is
	 *	  <code>null</code>
	 */
	public long getTimeToLive(String baseName, Locale locale) {
	    if (baseName == null || locale == null) {
		throw new NullPointerException();
	    }
	    return TTL_NO_EXPIRATION_CONTROL;
	}

	/**
	 * Determines if the expired <code>bundle</code> in the cache needs
	 * to be reloaded based on the loading time given by
	 * <code>loadTime</code> or some other criteria. The method returns
	 * <code>true</code> if reloading is required; <code>false</code>
	 * otherwise. <code>loadTime</code> is a millisecond offset since
	 * the <a href="Calendar.html#Epoch"> <code>Calendar</code>
	 * Epoch</a>.
	 *
	 * The calling <code>ResourceBundle.getBundle</code> factory method
	 * calls this method on the <code>ResourceBundle.Control</code>
	 * instance used for its current invocation, not on the instance
	 * used in the invocation that originally loaded the resource
	 * bundle.
	 *
	 * <p>The default implementation compares <code>loadTime</code> and
	 * the last modified time of the source data of the resource
	 * bundle. If it's determined that the source data has been modified
	 * since <code>loadTime</code>, <code>true</code> is
	 * returned. Otherwise, <code>false</code> is returned. This
	 * implementation assumes that the given <code>format</code> is the
	 * same string as its file suffix if it's not one of the default
	 * formats, <code>"java.class"</code> or
	 * <code>"java.properties"</code>.
	 *
         * @param baseName
	 *        the base bundle name of the resource bundle, a
         *        fully qualified class name
	 * @param locale
	 *        the locale for which the resource bundle
	 *        should be instantiated
         * @param format
	 *        the resource bundle format to be loaded
         * @param loader
	 *        the <code>ClassLoader</code> to use to load the bundle
	 * @param bundle
	 *        the resource bundle instance that has been expired
	 *        in the cache
	 * @param loadTime
	 *        the time when <code>bundle</code> was loaded and put
	 *        in the cache
	 * @return <code>true</code> if the expired bundle needs to be
	 *        reloaded; <code>false</code> otherwise.
         * @exception NullPointerException
	 *        if <code>baseName</code>, <code>locale</code>,
	 *        <code>format</code>, <code>loader</code>, or
	 *        <code>bundle</code> is <code>null</code>
	 */
	public boolean needsReload(String baseName, Locale locale,
				   String format, ClassLoader loader,
				   ResourceBundle bundle, long loadTime) {
	    if (bundle == null) {
		throw new NullPointerException();
	    }
	    if (format.equals("java.class") || format.equals("java.properties")) {
		format = format.substring(5);
	    }
	    boolean result = false;
	    try {
		String resourceName = toResourceName(toBundleName(baseName, locale), format);
		URL url = loader.getResource(resourceName);
		if (url != null) {
		    long lastModified = 0;
		    URLConnection connection = url.openConnection();
		    if (connection != null) {
			// disable caches to get the correct data
			connection.setUseCaches(false);
			if (connection instanceof JarURLConnection) {
			    JarEntry ent = ((JarURLConnection)connection).getJarEntry();
			    if (ent != null) {
				lastModified = ent.getTime();
				if (lastModified == -1) {
				    lastModified = 0;
				}
			    }
			} else {
			    lastModified = connection.getLastModified();
			}
		    }
		    result = lastModified >= loadTime;
		}
	    } catch (NullPointerException npe) {
		throw npe;
	    } catch (Exception e) {
		// ignore other exceptions
	    }
	    return result;
	}

        /**
         * Converts the given <code>baseName</code> and <code>locale</code>
         * to the bundle name. This method is called from the default
         * implementation of the {@link #newBundle(String, Locale, String,
         * ClassLoader, boolean) newBundle} and {@link #needsReload(String,
         * Locale, String, ClassLoader, ResourceBundle, long) needsReload}
         * methods.
	 *
	 * <p>This implementation returns the following value:
	 * <pre>
	 *     baseName + "_" + language + "_" + country + "_" + variant
	 * </pre>
	 * where <code>language</code>, <code>country</code> and
	 * <code>variant</code> are the language, country and variant values
	 * of <code>locale</code>, respectively. Final component values that
	 * are empty Strings are omitted along with the preceding '_'. If
	 * all of the values are empty strings, then <code>baseName</code>
	 * is returned.
	 *
	 * <p>For example, if <code>baseName</code> is
	 * <code>"baseName"</code> and <code>locale</code> is
	 * <code>Locale("ja",&nbsp;"",&nbsp;"XX")</code>, then
	 * <code>"baseName_ja_&thinsp;_XX"</code> is returned. If the given
	 * locale is <code>Locale("en")</code>, then
	 * <code>"baseName_en"</code> is returned.
         *
	 * <p>Overriding this method allows applications to use different
	 * conventions in the organization and packaging of localized
	 * resources.
	 *
         * @param baseName
	 *        the base name of the resource bundle, a fully
	 *        qualified class name
         * @param locale
	 *        the locale for which a resource bundle should be
	 *        loaded
         * @return the bundle name for the resource bundle
         * @exception NullPointerException
         *        if <code>baseName</code> or <code>locale</code>
         *        is <code>null</code>
         */
        public String toBundleName(String baseName, Locale locale) {
	    if (locale == Locale.ROOT) {
		return baseName;
	    }

	    String language = locale.getLanguage();
	    String country = locale.getCountry();
	    String variant = locale.getVariant();

	    if (language == "" && country == "" && variant == "") {
		return baseName;
	    }

	    StringBuilder sb = new StringBuilder(baseName);
	    sb.append('_');
	    if (variant != "") {
		sb.append(language).append('_').append(country).append('_').append(variant);
	    } else if (country != "") {
		sb.append(language).append('_').append(country);
	    } else {
		sb.append(language);
	    }
	    return sb.toString();

        }

	/**
	 * Converts the given <code>bundleName</code> to the form required
	 * by the {@link ClassLoader#getResource ClassLoader.getResource}
	 * method by replacing all occurrences of <code>'.'</code> in
	 * <code>bundleName</code> with <code>'/'</code> and appending a
	 * <code>'.'</code> and the given file <code>suffix</code>. For
	 * example, if <code>bundleName</code> is
	 * <code>"foo.bar.MyResources_ja_JP"</code> and <code>suffix</code>
	 * is <code>"properties"</code>, then
	 * <code>"foo/bar/MyResources_ja_JP.properties"</code> is returned.
	 *
	 * @param bundleName
	 *        the bundle name
	 * @param suffix
	 *        the file type suffix
	 * @return the converted resource name
	 * @exception NullPointerException
	 *         if <code>bundleName</code> or <code>suffix</code>
	 *         is <code>null</code>
	 */
	public final String toResourceName(String bundleName, String suffix) {
	    StringBuilder sb = new StringBuilder(bundleName.length() + 1 + suffix.length());
	    sb.append(bundleName.replace('.', '/')).append('.').append(suffix);
	    return sb.toString();
	}
    }

    private static class SingleFormatControl extends Control {
	private static final Control PROPERTIES_ONLY
	    = new SingleFormatControl(FORMAT_PROPERTIES);

	private static final Control CLASS_ONLY
	    = new SingleFormatControl(FORMAT_CLASS);

	private final List<String> formats;

	protected SingleFormatControl(List<String> formats) {
	    this.formats = formats;
	}

	public List<String> getFormats(String baseName) {
	    if (baseName == null) {
		throw new NullPointerException();
	    }
	    return formats;
	}
    }

    private static final class NoFallbackControl extends SingleFormatControl {
	private static final Control NO_FALLBACK
	    = new NoFallbackControl(FORMAT_DEFAULT);

	private static final Control PROPERTIES_ONLY_NO_FALLBACK
	    = new NoFallbackControl(FORMAT_PROPERTIES);

	private static final Control CLASS_ONLY_NO_FALLBACK
	    = new NoFallbackControl(FORMAT_CLASS);

	protected NoFallbackControl(List<String> formats) {
	    super(formats);
	}

	public Locale getFallbackLocale(String baseName, Locale locale) {
	    if (baseName == null || locale == null) {
		throw new NullPointerException();
	    }
	    return null;
	}
    }
}