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      1 /*
      2  * Copyright (c) 1998, 2011, 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<E>[] enums;
     37     private int index = 0;
     38 
     39     public CompoundEnumeration(Enumeration<E>[] 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 enums[index].nextElement();
     62     }
     63 }
     64