Java tutorial
/* * Copyright 2003-2004 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.bidimap; import java.util.Collection; import java.util.Map; import java.util.Set; import org.apache.commons.collections.BidiMap; import org.apache.commons.collections.MapIterator; import org.apache.commons.collections.Unmodifiable; import org.apache.commons.collections.collection.UnmodifiableCollection; import org.apache.commons.collections.iterators.UnmodifiableMapIterator; import org.apache.commons.collections.map.UnmodifiableEntrySet; import org.apache.commons.collections.set.UnmodifiableSet; /** * Decorates another <code>BidiMap</code> to ensure it can't be altered. * * @since Commons Collections 3.0 * @version $Revision: 1.5 $ $Date: 2004/05/15 12:13:03 $ * * @author Stephen Colebourne */ public final class UnmodifiableBidiMap extends AbstractBidiMapDecorator implements Unmodifiable { /** The inverse unmodifiable map */ private UnmodifiableBidiMap inverse; /** * Factory method to create an unmodifiable map. * <p> * If the map passed in is already unmodifiable, it is returned. * * @param map the map to decorate, must not be null * @return an unmodifiable BidiMap * @throws IllegalArgumentException if map is null */ public static BidiMap decorate(BidiMap map) { if (map instanceof Unmodifiable) { return map; } return new UnmodifiableBidiMap(map); } //----------------------------------------------------------------------- /** * Constructor that wraps (not copies). * * @param map the map to decorate, must not be null * @throws IllegalArgumentException if map is null */ private UnmodifiableBidiMap(BidiMap map) { super(map); } //----------------------------------------------------------------------- public void clear() { throw new UnsupportedOperationException(); } public Object put(Object key, Object value) { throw new UnsupportedOperationException(); } public void putAll(Map mapToCopy) { throw new UnsupportedOperationException(); } public Object remove(Object key) { throw new UnsupportedOperationException(); } public Set entrySet() { Set set = super.entrySet(); return UnmodifiableEntrySet.decorate(set); } public Set keySet() { Set set = super.keySet(); return UnmodifiableSet.decorate(set); } public Collection values() { Collection coll = super.values(); return UnmodifiableCollection.decorate(coll); } //----------------------------------------------------------------------- public Object removeValue(Object value) { throw new UnsupportedOperationException(); } public MapIterator mapIterator() { MapIterator it = getBidiMap().mapIterator(); return UnmodifiableMapIterator.decorate(it); } public BidiMap inverseBidiMap() { if (inverse == null) { inverse = new UnmodifiableBidiMap(getBidiMap().inverseBidiMap()); inverse.inverse = this; } return inverse; } }