arrayenumeration.java

来自「java写的crawler」· Java 代码 · 共 71 行

/*
 * Copyright (c) 1998-2002 Carnegie Mellon University.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY
 * NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

package rcm.enum;
import java.util.Enumeration;
import java.util.NoSuchElementException;

/**
 * Enumeration of an arbitrary array.
 */
public class ArrayEnumeration implements Enumeration {
    Object[] array;
    int i = 0;

    /**
     * Make an ArrayEnumeration.
     * @param array Array to enumerate.  May be null, if desired.  
     * (This is sometimes useful for producing an empty enumeration.)
     */
    public ArrayEnumeration (Object[] array) {
        this.array = array;
    }

    /**
     * Test if enumeration has reached end.
     * @return true if more elements are available to be enumerated, false
     * if all elements have been yielded by nextElement()
     */
    public boolean hasMoreElements () {
        return array != null ? i < array.length : false;
    }

    /**
     * Get next element of enumeration.
     * @return next element of enumeration, advancing the enumeration pointer
     * @exception java.util.NoSuchElementException if no more elements
     */
    public Object nextElement () {
        if (array == null || i >= array.length)
            throw new NoSuchElementException ();
        return array[i++];
    }
}