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HSQLDB example source code file (WrapperIterator.java)
The HSQLDB WrapperIterator.java source code/* Copyright (c) 2001-2008, The HSQL Development Group * 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 the HSQL Development Group 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 HSQL DEVELOPMENT GROUP, HSQLDB.ORG, * 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. */ package org.hsqldb.lib; import java.util.NoSuchElementException; /** * An Iterator that returns the elements of a specified array, or other * iterators etc. The collection of objects returned depends on the * constructor used.<p> * * Based on similar Enumerator code by boucherb@users * * @author fred@users * @version 1.9.0 * @since HSQLDB 1.7.2 */ public class WrapperIterator implements Iterator { private static final Object[] emptyelements = new Object[0]; private Object[] elements; private int i; // chained iterators private boolean chained; private Iterator it1; private Iterator it2; /** return only not null elements */ private boolean notNull; /** * Constructor for an empty iterator. <p> */ public WrapperIterator() { this.elements = emptyelements; } /** * Constructor for all elements of the specified array. <p> * * @param elements the array of objects to enumerate */ public WrapperIterator(Object[] elements) { this.elements = elements; } /** * Constructor for not-null elements of specified array. <p> * * @param elements the array of objects to iterate */ public WrapperIterator(Object[] elements, boolean notNull) { this.elements = elements; this.notNull = notNull; } /** * Constructor for a singleton object iterator * * @param element the single object to iterate */ public WrapperIterator(Object element) { this.elements = new Object[]{ element }; } /** * Constructor for a chained iterator that returns the elements of the two * specified iterators. */ public WrapperIterator(Iterator it1, Iterator it2) { this.it1 = it1; this.it2 = it2; chained = true; } /** * Tests if this iterator contains more elements. <p> * * @return <code>true if this iterator contains more elements; * <code>false otherwise. */ public boolean hasNext() { // for chained iterators if (chained) { if (it1 == null) { if (it2 == null) { return false; } if (it2.hasNext()) { return true; } it2 = null; return false; } else { if (it1.hasNext()) { return true; } it1 = null; return hasNext(); } } // for other interators if (elements == null) { return false; } for (; notNull && i < elements.length && elements[i] == null; i++) {} if (i < elements.length) { return true; } else { // release elements for garbage collection elements = null; return false; } } /** * Returns the next element. * * @return the next element * @throws NoSuchElementException if there is no next element */ public Object next() { // for chained iterators if (chained) { if (it1 == null) { if (it2 == null) { throw new NoSuchElementException(); } if (it2.hasNext()) { return it2.next(); } it2 = null; next(); } else { if (it1.hasNext()) { return it1.next(); } it1 = null; next(); } } // for other itertors if (hasNext()) { return elements[i++]; } throw new NoSuchElementException(); } public int nextInt() { throw new NoSuchElementException(); } public long nextLong() { throw new NoSuchElementException(); } public void remove() { throw new NoSuchElementException(); } public void setValue(Object value) { throw new NoSuchElementException(); } } Other HSQLDB examples (source code examples)Here is a short list of links related to this HSQLDB WrapperIterator.java source code file: |
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