All Downloads are FREE. Search and download functionalities are using the official Maven repository.

org.apache.commons.collections.set.ListOrderedSet Maven / Gradle / Ivy

There is a newer version: 20040616
Show newest version
/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2003-2004 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 */
package org.apache.commons.collections.set;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import org.apache.commons.collections.iterators.AbstractIteratorDecorator;
import org.apache.commons.collections.list.UnmodifiableList;

/**
 * Decorates another Set to ensure that the order of addition
 * is retained and used by the iterator.
 * 

* If an object is added to the set for a second time, it will remain in the * original position in the iteration. * The order can be observed from the set via the iterator or toArray methods. *

* The ListOrderedSet also has various useful direct methods. These include many * from List, such as get(int), remove(int) * and indexOf(int). An unmodifiable List view of * the set can be obtained via asList(). *

* This class cannot implement the List interface directly as * various interface methods (notably equals/hashCode) are incompatable with a set. * * @since Commons Collections 3.0 * @version $Revision: 1.5 $ $Date: 2004/01/14 21:43:14 $ * * @author Stephen Colebourne * @author Henning P. Schmiedehausen */ public class ListOrderedSet extends AbstractSetDecorator implements Set { /** Internal list to hold the sequence of objects */ protected final List setOrder; /** * Factory method to create an ordered set. *

* An ArrayList is used to retain order. * * @param set the set to decorate, must not be null * @throws IllegalArgumentException if set is null */ public static ListOrderedSet decorate(Set set) { return new ListOrderedSet(set); } /** * Factory method to create an ordered set using the supplied list to retain order. *

* A HashSet is used for the set behaviour. * * @param list the list to decorate, must not be null * @throws IllegalArgumentException if set is null */ public static ListOrderedSet decorate(List list) { Set set = new HashSet(list); list.retainAll(set); return new ListOrderedSet(set, list); } //----------------------------------------------------------------------- /** * Constructor that wraps (not copies). * * @param set the set to decorate, must not be null * @throws IllegalArgumentException if set is null */ protected ListOrderedSet(Set set) { super(set); setOrder = new ArrayList(set); } /** * Constructor that wraps (not copies) the Set and specifies the list to use. *

* The set and list must both be correctly initialised to the same elements. * * @param set the set to decorate, must not be null * @param list the list to decorate, must not be null * @throws IllegalArgumentException if set or list is null */ protected ListOrderedSet(Set set, List list) { super(set); if (list == null) { throw new IllegalArgumentException("List must not be null"); } setOrder = list; } //----------------------------------------------------------------------- /** * Gets an unmodifiable view of the order of the Set. * * @return an unmodifiable list view */ public List asList() { return UnmodifiableList.decorate(setOrder); } //----------------------------------------------------------------------- public void clear() { collection.clear(); setOrder.clear(); } public Iterator iterator() { return new OrderedSetIterator(setOrder.iterator(), collection); } public boolean add(Object object) { if (collection.contains(object)) { // re-adding doesn't change order return collection.add(object); } else { // first add, so add to both set and list boolean result = collection.add(object); setOrder.add(object); return result; } } public boolean addAll(Collection coll) { boolean result = false; for (Iterator it = coll.iterator(); it.hasNext();) { Object object = it.next(); result = result | add(object); } return result; } public boolean remove(Object object) { boolean result = collection.remove(object); setOrder.remove(object); return result; } public boolean removeAll(Collection coll) { boolean result = false; for (Iterator it = coll.iterator(); it.hasNext();) { Object object = it.next(); result = result | remove(object); } return result; } public boolean retainAll(Collection coll) { boolean result = collection.retainAll(coll); if (result == false) { return false; } else if (collection.size() == 0) { setOrder.clear(); } else { for (Iterator it = setOrder.iterator(); it.hasNext();) { Object object = it.next(); if (collection.contains(object) == false) { it.remove(); } } } return result; } public Object[] toArray() { return setOrder.toArray(); } public Object[] toArray(Object a[]) { return setOrder.toArray(a); } //----------------------------------------------------------------------- public Object get(int index) { return setOrder.get(index); } public int indexOf(Object object) { return setOrder.indexOf(object); } public void add(int index, Object object) { if (contains(object) == false) { collection.add(object); setOrder.add(index, object); } } public boolean addAll(int index, Collection coll) { boolean changed = false; for (Iterator it = coll.iterator(); it.hasNext();) { Object object = it.next(); if (contains(object) == false) { collection.add(object); setOrder.add(index, object); index++; changed = true; } } return changed; } public Object remove(int index) { Object obj = setOrder.remove(index); remove(obj); return obj; } /** * Uses the underlying List's toString so that order is achieved. * This means that the decorated Set's toString is not used, so * any custom toStrings will be ignored. */ // Fortunately List.toString and Set.toString look the same public String toString() { return setOrder.toString(); } //----------------------------------------------------------------------- /** * Internal iterator handle remove. */ static class OrderedSetIterator extends AbstractIteratorDecorator { /** Object we iterate on */ protected final Collection set; /** Last object retrieved */ protected Object last; private OrderedSetIterator(Iterator iterator, Collection set) { super(iterator); this.set = set; } public Object next() { last = iterator.next(); return last; } public void remove() { set.remove(last); iterator.remove(); last = null; } } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy