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 }