1 /*
2  * Copyright (c) 2001, 2005, Oracle and/or its affiliates. All rights reserved.
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * This code is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License version 2 only, as
7  * published by the Free Software Foundation.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 
26 package sun.util;
27 
28 import java.util.Enumeration;
29 import java.util.Iterator;
30 import java.util.NoSuchElementException;
31 import java.util.Set;
32 
33 /**
34  * Implements an Enumeration that combines elements from a Set and
35  * an Enumeration. Used by ListResourceBundle and PropertyResourceBundle.
36  */
37 public class ResourceBundleEnumeration implements Enumeration<String> {
38 
39     Set<String> set;
40     Iterator<String> iterator;
41     Enumeration<String> enumeration; // may remain null
42 
43     /**
44      * Constructs a resource bundle enumeration.
45      * @param set an set providing some elements of the enumeration
46      * @param enumeration an enumeration providing more elements of the enumeration.
47      *        enumeration may be null.
48      */
ResourceBundleEnumeration(Set<String> set, Enumeration<String> enumeration)49     public ResourceBundleEnumeration(Set<String> set, Enumeration<String> enumeration) {
50         this.set = set;
51         this.iterator = set.iterator();
52         this.enumeration = enumeration;
53     }
54 
55     String next = null;
56 
hasMoreElements()57     public boolean hasMoreElements() {
58         if (next == null) {
59             if (iterator.hasNext()) {
60                 next = iterator.next();
61             } else if (enumeration != null) {
62                 while (next == null && enumeration.hasMoreElements()) {
63                     next = enumeration.nextElement();
64                     if (set.contains(next)) {
65                         next = null;
66                     }
67                 }
68             }
69         }
70         return next != null;
71     }
72 
nextElement()73     public String nextElement() {
74         if (hasMoreElements()) {
75             String result = next;
76             next = null;
77             return result;
78         } else {
79             throw new NoSuchElementException();
80         }
81     }
82 }
83