edu.psu.chemxseer.structure.util.ArrayIterator.java Source code

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Here is the source code for edu.psu.chemxseer.structure.util.ArrayIterator.java

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package edu.psu.chemxseer.structure.util;

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

import java.lang.reflect.Array;
import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * Implements an {@link java.util.Iterator Iterator} over any array.
 * 
 * The array can be either an array of object or of primitives. If you know that
 * you have an object array, the
 * {@link org.apache.commons.collections.iterators.ObjectArrayIterator
 * ObjectArrayIterator} class is a better choice, as it will perform better.
 * 
 * The iterator implements a {@link #reset} method, allowing the reset of the
 * iterator back to the start if required.
 * 
 * @since Commons Collections 1.0
 * @version $Revision$ $Date$
 * 
 * @author James Strachan
 * @author Mauricio S. Moura
 * @author Michael A. Smith
 * @author Neil O'Toole
 * @author Stephen Colebourne
 * @param <T>
 */
@SuppressWarnings("rawtypes")
public class ArrayIterator implements Iterator {

    /** The array to iterate over */
    protected Object array;
    /** The end index to loop to */
    protected int endIndex = 0;
    /** The current iterator index */
    protected int index = 0;

    /**
     * Constructs an ArrayIterator that will iterate over the values in the
     * specified array.
     * 
     * @param array
     *            the array to iterate over.
     * @throws IllegalArgumentException
     *             if <code>array</code> is not an array.
     * @throws NullPointerException
     *             if <code>array</code> is <code>null</code>
     */
    public ArrayIterator(final Object array) {
        setArray(array);
    }

    /**
     * Checks whether the index is valid or not.
     * 
     * @param bound
     *            the index to check
     * @param type
     *            the index type (for error messages)
     * @throws IndexOutOfBoundsException
     *             if the index is invalid
     */
    protected void checkBound(final int bound, final String type) {
        if (bound > this.endIndex) {
            throw new ArrayIndexOutOfBoundsException(
                    "Attempt to make an ArrayIterator that " + type + "s beyond the end of the array. ");
        }
        if (bound < 0) {
            throw new ArrayIndexOutOfBoundsException(
                    "Attempt to make an ArrayIterator that " + type + "s before the start of the array. ");
        }
    }

    // Iterator interface
    // -----------------------------------------------------------------------
    /**
     * Returns true if there are more elements to return from the array.
     * 
     * @return true if there is a next element to return
     */
    @Override
    public boolean hasNext() {
        return (index < endIndex);
    }

    /**
     * Returns the next element in the array.
     * 
     * @return the next element in the array
     * @throws NoSuchElementException
     *             if all the elements in the array have already been returned
     */
    @Override
    public Object next() {
        if (hasNext() == false) {
            throw new NoSuchElementException();
        }
        return Array.get(array, index++);
    }

    /**
     * Throws {@link UnsupportedOperationException}.
     * 
     * @throws UnsupportedOperationException
     *             always
     */
    @Override
    public void remove() {
        throw new UnsupportedOperationException("remove() method is not supported");
    }

    // Properties
    // -----------------------------------------------------------------------
    /**
     * Gets the array that this iterator is iterating over.
     * 
     * @return the array this iterator iterates over, or <code>null</code> if
     *         the no-arg constructor was used and {@link #setArray(Object)} has
     *         never been called with a valid array.
     */
    public Object getArray() {
        return array;
    }

    /**
     * Sets the array that the ArrayIterator should iterate over.
     * 
     * If an array has previously been set (using the single-arg constructor or
     * this method) then that array is discarded in favour of this one.
     * Iteration is restarted at the start of the new array. Although this can
     * be used to reset iteration, the {@link #clear()} method is a more
     * effective choice.
     * 
     * @param array
     *            the array that the iterator should iterate over.
     * @throws IllegalArgumentException
     *             if <code>array</code> is not an array.
     * @throws NullPointerException
     *             if <code>array</code> is <code>null</code>
     */
    private void setArray(final Object array) {
        // Array.getLength throws IllegalArgumentException if the object is not
        // an array or NullPointerException if the object is null. This call
        // is made before saving the array and resetting the index so that the
        // array iterator remains in a consistent state if the argument is not
        // an array or is null.
        this.endIndex = Array.getLength(array);
        this.array = array;
        this.index = 0;
    }

}