Mega Code Archive
Iterator class for sparse values in an array
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/*
* 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
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* 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
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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*/
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);
}
}
}
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