ArrayIterator.java Source code

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Here is the source code for ArrayIterator.java

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/*
 * Converts an array to an iterator.
 * Copyright (C) 2004-2006 Stephen Ostermiller
 * http://ostermiller.org/contact.pl?regarding=Java+Utilities
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * See COPYING.TXT for details.
 */

import java.util.*;

/**
 * Converts an array to an iterator.
 * <p>
 * More information about this class is available from <a target="_top" href=
 * "http://ostermiller.org/utils/Iterator_Enumeration.html">ostermiller.org</a>.
 *
 * @author Stephen Ostermiller http://ostermiller.org/contact.pl?regarding=Java+Utilities
 * @param <ElementType> Type of array over which to iterate
 * @since ostermillerutils 1.03.00
 */
public class ArrayIterator<ElementType> implements Iterator<ElementType> {

    /**
     * Array being converted to iterator.
     */
    private ElementType[] array;

    /**
     * Current index into the array.
     */
    private int index = 0;

    /**
     * Whether the last element has been removed.
     */
    private boolean lastRemoved = false;

    /**
     * Create an Iterator from an Array.
     *
     * @param array of objects on which to enumerate.
     *
     * @since ostermillerutils 1.03.00
     */
    public ArrayIterator(ElementType[] array) {
        this.array = array;
    }

    /**
     * Tests if this Iterator contains more elements.
     *
     * @return true if and only if this Iterator object contains at least
     * one more element to provide; false otherwise.
     *
     * @since ostermillerutils 1.03.00
     */
    public boolean hasNext() {
        return (index < array.length);
    }

    /**
     * Returns the next element of this Iterator if this Iterator
     * object has at least one more element to provide.
     *
     * @return the next element of this Iterator.
     * @throws NoSuchElementException if no more elements exist.
     *
     * @since ostermillerutils 1.03.00
     */
    public ElementType next() throws NoSuchElementException {
        if (index >= array.length)
            throw new NoSuchElementException("Array index: " + index);
        ElementType object = array[index];
        index++;
        lastRemoved = false;
        return object;
    }

    /**
     * Removes the last object from the array by setting the slot in
     * the array to null.
     * This method can be called only once per call to next.
     *
     * @throws IllegalStateException if the next method has not yet been called, or the remove method has already been called after the last call to the next method.
     *
     * @since ostermillerutils 1.03.00
     */
    public void remove() {
        if (index == 0)
            throw new IllegalStateException();
        if (lastRemoved)
            throw new IllegalStateException();
        array[index - 1] = null;
        lastRemoved = true;
    }
}