ResourceBundleEnumeration


1   /*
2    * @(#)ResourceBundleEnumeration.java   1.5 04/05/05
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.util;
9   
10  /**
11   * Implements an Enumeration that combines elements from a Set and
12   * an Enumeration. Used by ListResourceBundle and PropertyResourceBundle.
13   */
14  class ResourceBundleEnumeration implements Enumeration  <String  > {
15  
16      Set  <String  > set;
17      Iterator  <String  > iterator;
18      Enumeration  <String  > enumeration; // may remain null
19  
20      /**
21       * Constructs a resource bundle enumeration.
22       * @param set an set providing some elements of the enumeration
23       * @param enumeration an enumeration providing more elements of the enumeration.
24       *        enumeration may be null.
25       */
26      ResourceBundleEnumeration(Set  <String  > set, Enumeration  <String  > enumeration) {
27          this.set = set;
28          this.iterator = set.iterator();
29          this.enumeration = enumeration;
30      }
31  
32      String   next = null;
33              
34      public boolean hasMoreElements() {
35          if (next == null) {
36              if (iterator.hasNext()) {
37                  next = iterator.next();
38              } else if (enumeration != null) {
39                  while (next == null && enumeration.hasMoreElements()) {
40                      next = enumeration.nextElement();
41                      if (set.contains(next)) {
42                          next = null;
43                      }
44                  }
45              }
46          }
47          return next != null;
48      }
49  
50      public String   nextElement() {
51          if (hasMoreElements()) {
52              String   result = next;
53              next = null;
54              return result;
55          } else {
56              throw new NoSuchElementException  ();
57          }
58      }
59  }
60
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