/*

 * Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.misc;

import java.util.Enumeration;

import java.util.NoSuchElementException;

/*

 * A useful utility class that will enumerate over an array of

 * enumerations.

 */

public class CompoundEnumeration<E> implements Enumeration<E> {

    private Enumeration<E>[] enums;

    private int index = 0;

    public CompoundEnumeration(Enumeration<E>[] enums) {

        this.enums = enums;

    }

    private boolean next() {

        while (index < enums.length) {

            if (enums[index] != null && enums[index].hasMoreElements()) {

                return true;

            }

            index++;

        }

        return false;

    }

    public boolean hasMoreElements() {

        return next();

    }

    public E nextElement() {

        if (!next()) {

            throw new NoSuchElementException();

        }

        return enums[index].nextElement();

    }

}