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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       */
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  
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  
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  }