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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 }
     83