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
26package sun.misc;
27
28import java.util.Enumeration;
29import java.util.NoSuchElementException;
30
31/*
32 * A useful utility class that will enumerate over an array of
33 * enumerations.
34 */
35public 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}
64