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 * Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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/*
 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996 - 1998 - 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 sun.util.ResourceBundleEnumeration;

/**
 * <code>ListResourceBundle</code> is an abstract subclass of
 * <code>ResourceBundle</code> that manages resources for a locale
 * in a convenient and easy to use list. See <code>ResourceBundle</code> for
 * more information about resource bundles in general.
 *
 * <P>
 * Subclasses must override <code>getContents</code> and provide an array,
 * where each item in the array is a pair of objects.
 * The first element of each pair is the key, which must be a
 * <code>String</code>, and the second element is the value associated with
 * that key.
 *
 * <p>
 * The following <a id="sample">example</a> shows two members of a resource
 * bundle family with the base name "MyResources".
 * "MyResources" is the default member of the bundle family, and
 * "MyResources_fr" is the French member.
 * These members are based on <code>ListResourceBundle</code>
 * (a related <a href="PropertyResourceBundle.html#sample">example</a> shows
 * how you can add a bundle to this family that's based on a properties file).
 * The keys in this example are of the form "s1" etc. The actual
 * keys are entirely up to your choice, so long as they are the same as
 * the keys you use in your program to retrieve the objects from the bundle.
 * Keys are case-sensitive.
 * <blockquote>
 * <pre>
 *
 * public class MyResources extends ListResourceBundle {
 * protected Object[][] getContents() {
 * return new Object[][] {
 * // LOCALIZE THIS
 * {"s1", "The disk \"{1}\" contains {0}."}, // MessageFormat pattern
 * {"s2", "1"}, // location of {0} in pattern
 * {"s3", "My Disk"}, // sample disk name
 * {"s4", "no files"}, // first ChoiceFormat choice
 * {"s5", "one file"}, // second ChoiceFormat choice
 * {"s6", "{0,number} files"}, // third ChoiceFormat choice
 * {"s7", "3 Mar 96"}, // sample date
 * {"s8", new Dimension(1,5)} // real object, not just string
 * // END OF MATERIAL TO LOCALIZE
 * };
 * }
 * }
 *
 * public class MyResources_fr extends ListResourceBundle {
 * protected Object[][] getContents() {
 * return new Object[][] {
 * // LOCALIZE THIS
 * {"s1", "Le disque \"{1}\" {0}."}, // MessageFormat pattern
 * {"s2", "1"}, // location of {0} in pattern
 * {"s3", "Mon disque"}, // sample disk name
 * {"s4", "ne contient pas de fichiers"}, // first ChoiceFormat choice
 * {"s5", "contient un fichier"}, // second ChoiceFormat choice
 * {"s6", "contient {0,number} fichiers"}, // third ChoiceFormat choice
 * {"s7", "3 mars 1996"}, // sample date
 * {"s8", new Dimension(1,3)} // real object, not just string
 * // END OF MATERIAL TO LOCALIZE
 * };
 * }
 * }
 * </pre>
 * </blockquote>
 *
 * <p>
 * The implementation of a {@code ListResourceBundle} subclass must be thread-safe
 * if it's simultaneously used by multiple threads. The default implementations
 * of the methods in this class are thread-safe.
 *
 * @see ResourceBundle
 * @see PropertyResourceBundle
 * @since 1.1
 */
public abstract class ListResourceBundle extends ResourceBundle {
 /**
 * Sole constructor. (For invocation by subclass constructors, typically
 * implicit.)
 */
 public ListResourceBundle() {
 }

 // Implements java.util.ResourceBundle.handleGetObject; inherits javadoc specification.
 public final Object handleGetObject(String key) {
 // lazily load the lookup hashtable.
 if (lookup == null) {
 loadLookup();
 }
 if (key == null) {
 throw new NullPointerException();
 }
 return lookup.get(key); // this class ignores locales
 }

 /**
 * Returns an <code>Enumeration</code> of the keys contained in
 * this <code>ResourceBundle</code> and its parent bundles.
 *
 * @return an <code>Enumeration</code> of the keys contained in
 * this <code>ResourceBundle</code> and its parent bundles.
 * @see #keySet()
 */
 public Enumeration<String> getKeys() {
 // lazily load the lookup hashtable.
 if (lookup == null) {
 loadLookup();
 }

 ResourceBundle parent = this.parent;
 return new ResourceBundleEnumeration(lookup.keySet(),
 (parent != null) ? parent.getKeys() : null);
 }

 /**
 * Returns a <code>Set</code> of the keys contained
 * <em>only</em> in this <code>ResourceBundle</code>.
 *
 * @return a <code>Set</code> of the keys contained only in this
 * <code>ResourceBundle</code>
 * @since 1.6
 * @see #keySet()
 */
 protected Set<String> handleKeySet() {
 if (lookup == null) {
 loadLookup();
 }
 return lookup.keySet();
 }

 /**
 * Returns an array in which each item is a pair of objects in an
 * <code>Object</code> array. The first element of each pair is
 * the key, which must be a <code>String</code>, and the second
 * element is the value associated with that key. See the class
 * description for details.
 *
 * @return an array of an <code>Object</code> array representing a
 * key-value pair.
 */
 protected abstract Object[][] getContents();

 // ==================privates====================

 /**
 * We lazily load the lookup hashtable. This function does the
 * loading.
 */
 private synchronized void loadLookup() {
 if (lookup != null)
 return;

 Object[][] contents = getContents();
 HashMap<String,Object> temp = new HashMap<>(contents.length);
 for (Object[] content : contents) {
 // key must be non-null String, value must be non-null
 String key = (String) content[0];
 Object value = content[1];
 if (key == null || value == null) {
 throw new NullPointerException();
 }
 temp.put(key, value);
 }
 lookup = temp;
 }

 private volatile Map<String,Object> lookup = null;
}