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    1   /*
    2    * Copyright (c) 1998, 2004, 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.misc;
   27   
   28   import java.util.Enumeration;
   29   import java.util.NoSuchElementException;
   30   
   31   /*
   32    * A useful utility class that will enumerate over an array of
   33    * enumerations.
   34    */
   35   public class CompoundEnumeration<E> implements Enumeration<E> {
   36       private Enumeration[] enums;
   37       private int index = 0;
   38   
   39       public CompoundEnumeration(Enumeration[] enums) {
   40           this.enums = enums;
   41       }
   42   
   43       private boolean next() {
   44           while (index < enums.length) {
   45               if (enums[index] != null && enums[index].hasMoreElements()) {
   46                   return true;
   47               }
   48               index++;
   49           }
   50           return false;
   51       }
   52   
   53       public boolean hasMoreElements() {
   54           return next();
   55       }
   56   
   57       public E nextElement() {
   58           if (!next()) {
   59               throw new NoSuchElementException();
   60           }
   61           return (E)enums[index].nextElement();
   62       }
   63   }

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