Iterator class for sparse values in an array. : Iterator « Collections Data Structure « Java






Iterator class for sparse values in an array.

    
/*
 * Copyright (c) 2000-2007, Dennis M. Sosnoski. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer. 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. Neither the name of JiBX nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS 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 THE COPYRIGHT OWNER OR CONTRIBUTORS 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.
 */


import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * Iterator class for sparse values in an array. This type of iterator
 * can be used for an object array which has references interspersed with
 * <code>null</code>s.
 *
 * @author Dennis M. Sosnoski
 */
public class SparseArrayIterator implements Iterator
{
    /** Empty iterator. */
    public static final SparseArrayIterator EMPTY_ITERATOR =
        new SparseArrayIterator(new Object[0]);
    
    /** Array supplying values for iteration. */
    private Object[] m_array;

    /** Offset of next iteration value. */
    private int m_offset;

    /**
     * Internal constructor.
     *
     * @param array array containing values to be iterated
     */
    private SparseArrayIterator(Object[] array) {
        m_array = array;
        m_offset = -1;
        advance();
    }

    /**
     * Advance to next iteration value. This advances the current position in
     * the array to the next non-<code>null</code> value.
     *
     * @return <code>true</code> if element available, <code>false</code> if
     * not
     */
    protected boolean advance() {
        while (++m_offset < m_array.length) {
            if (m_array[m_offset] != null) {
                return true;
            }
        }
        return false;
    }

    /**
     * Check for iteration element available.
     *
     * @return <code>true</code> if element available, <code>false</code> if
     * not
     */
    public boolean hasNext() {
        return m_offset < m_array.length;
    }

    /**
     * Get next iteration element.
     *
     * @return next iteration element
     * @exception NoSuchElementException if past end of iteration
     */
    public Object next() {
        if (m_offset < m_array.length) {
            Object result = m_array[m_offset];
            advance();
            return result;
        } else {
            throw new NoSuchElementException();
        }
    }

    /**
     * Remove element from iteration. This optional operation is not supported
     * and always throws an exception.
     *
     * @exception UnsupportedOperationException for unsupported operation
     */
    public void remove() {
        throw new UnsupportedOperationException();
    }

    /**
     * Build iterator.
     *
     * @param array array containing values to be iterated (may be
     * <code>null</code>)
     * @return constructed iterator
     */
    public static Iterator buildIterator(Object[] array) {
        if (array == null || array.length == 0) {
            return EMPTY_ITERATOR;
        } else {
            return new SparseArrayIterator(array);
        }
    }
}

   
    
    
    
  








Related examples in the same category

1.Listing the Elements of a Collection
2.De-mystify the Iterator interface, showing how to write a simple Iterator for an Array of Objects
3.Iterate over Set
4.Demonstrate iterators.
5.Use the for-each for loop to cycle through a collection.
6.List IteratorList Iterator
7.Iterate a Collection and remove an item (Exception, wrong version)
8.Use an Iterator and remove the item with Iterator.remove()
9.An Iterator wrapper for an Enumeration.
10.EmptyIterator is an iterator which is empty.
11.Implements an java.util.Iterator over any array
12.Treat an Iterator as an Iterable
13.Iterator class for values contained in an array range.
14.Array Iterator
15.Cyclic Iteration
16.Create singleton Iterator
17.Empty Iterator
18.An Iterator that wraps a number of Iterators
19.An Iterator to iterate over the elements of an array
20.Sorted Iterator
21.Iterator Union of Iterators
22.Iterator Utils
23.Linked Iterator
24.Prefetch Iterator
25.Protects an given iterator by preventing calls to remove().
26.An Iterator that returns the elements of a specified array, or other iterators etc.
27.An Iterator wrapper for an Object[], allow us to deal with all array like structures in a consistent manner.
28.An array iterator
29.Adapt iterator to iterable
30.Static utility methods, classes, and abstract classes for iteration.
31.Iterator Collection
32.Convert Iterable to List
33.A singleton null object Iterator implementation.