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 
CompoundEnumeration(Enumeration<E>[] enums)39     public CompoundEnumeration(Enumeration<E>[] enums) {
40         this.enums = enums;
41     }
42 
next()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 
hasMoreElements()53     public boolean hasMoreElements() {
54         return next();
55     }
56 
nextElement()57     public E nextElement() {
58         if (!next()) {
59             throw new NoSuchElementException();
60         }
61         return enums[index].nextElement();
62     }
63 }
64