| /* |
| * Copyright 2004 The Apache Software Foundation |
| * |
| * Licensed 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. |
| */ |
| package org.apache.commons.collections.set; |
| |
| import java.io.Serializable; |
| import java.util.Collection; |
| import java.util.Iterator; |
| import java.util.Map; |
| import java.util.Set; |
| |
| /** |
| * Decorates a <code>Map</code> to obtain <code>Set</code> behaviour. |
| * <p> |
| * This class is used to create a <code>Set</code> with the same properties as |
| * the key set of any map. Thus, a ReferenceSet can be created by wrapping a |
| * <code>ReferenceMap</code> in an instance of this class. |
| * <p> |
| * Most map implementation can be used to create a set by passing in dummy values. |
| * Exceptions include <code>BidiMap</code> implementations, as they require unique values. |
| * |
| * @since Commons Collections 3.1 |
| * @version $Revision: 1.1 $ $Date: 2009/05/27 22:16:31 $ |
| * |
| * @author Stephen Colebourne |
| */ |
| public final class MapBackedSet implements Set, Serializable { |
| |
| /** Serialization version */ |
| private static final long serialVersionUID = 6723912213766056587L; |
| |
| /** The map being used as the backing store */ |
| protected final Map map; |
| /** The dummyValue to use */ |
| protected final Object dummyValue; |
| |
| /** |
| * Factory method to create a set from a map. |
| * |
| * @param map the map to decorate, must not be null |
| * @throws IllegalArgumentException if set is null |
| */ |
| public static Set decorate(Map map) { |
| return decorate(map, null); |
| } |
| |
| /** |
| * Factory method to create a set from a map. |
| * |
| * @param map the map to decorate, must not be null |
| * @param dummyValue the dummy value to use |
| * @throws IllegalArgumentException if map is null |
| */ |
| public static Set decorate(Map map, Object dummyValue) { |
| if (map == null) { |
| throw new IllegalArgumentException("The map must not be null"); |
| } |
| return new MapBackedSet(map, dummyValue); |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Constructor that wraps (not copies). |
| * |
| * @param map the map to decorate, must not be null |
| * @param dummyValue the dummy value to use |
| * @throws IllegalArgumentException if map is null |
| */ |
| private MapBackedSet(Map map, Object dummyValue) { |
| super(); |
| this.map = map; |
| this.dummyValue = dummyValue; |
| } |
| |
| //----------------------------------------------------------------------- |
| public int size() { |
| return map.size(); |
| } |
| |
| public boolean isEmpty() { |
| return map.isEmpty(); |
| } |
| |
| public Iterator iterator() { |
| return map.keySet().iterator(); |
| } |
| |
| public boolean contains(Object obj) { |
| return map.containsKey(obj); |
| } |
| |
| public boolean containsAll(Collection coll) { |
| return map.keySet().containsAll(coll); |
| } |
| |
| public boolean add(Object obj) { |
| int size = map.size(); |
| map.put(obj, dummyValue); |
| return (map.size() != size); |
| } |
| |
| public boolean addAll(Collection coll) { |
| int size = map.size(); |
| for (Iterator it = coll.iterator(); it.hasNext();) { |
| Object obj = it.next(); |
| map.put(obj, dummyValue); |
| } |
| return (map.size() != size); |
| } |
| |
| public boolean remove(Object obj) { |
| int size = map.size(); |
| map.remove(obj); |
| return (map.size() != size); |
| } |
| |
| public boolean removeAll(Collection coll) { |
| return map.keySet().removeAll(coll); |
| } |
| |
| public boolean retainAll(Collection coll) { |
| return map.keySet().retainAll(coll); |
| } |
| |
| public void clear() { |
| map.clear(); |
| } |
| |
| public Object[] toArray() { |
| return map.keySet().toArray(); |
| } |
| |
| public Object[] toArray(Object[] array) { |
| return map.keySet().toArray(array); |
| } |
| |
| public boolean equals(Object obj) { |
| return map.keySet().equals(obj); |
| } |
| |
| public int hashCode() { |
| return map.keySet().hashCode(); |
| } |
| |
| } |