001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.collections.bag; 018 019 import java.io.IOException; 020 import java.io.ObjectInputStream; 021 import java.io.ObjectOutputStream; 022 import java.io.Serializable; 023 import java.util.Collection; 024 import java.util.Iterator; 025 import java.util.Set; 026 027 import org.apache.commons.collections.Bag; 028 import org.apache.commons.collections.Unmodifiable; 029 import org.apache.commons.collections.iterators.UnmodifiableIterator; 030 import org.apache.commons.collections.set.UnmodifiableSet; 031 032 /** 033 * Decorates another <code>Bag</code> to ensure it can't be altered. 034 * <p> 035 * This class is Serializable from Commons Collections 3.1. 036 * 037 * @since Commons Collections 3.0 038 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ 039 * 040 * @author Stephen Colebourne 041 */ 042 public final class UnmodifiableBag 043 extends AbstractBagDecorator implements Unmodifiable, Serializable { 044 045 /** Serialization version */ 046 private static final long serialVersionUID = -1873799975157099624L; 047 048 /** 049 * Factory method to create an unmodifiable bag. 050 * <p> 051 * If the bag passed in is already unmodifiable, it is returned. 052 * 053 * @param bag the bag to decorate, must not be null 054 * @return an unmodifiable Bag 055 * @throws IllegalArgumentException if bag is null 056 */ 057 public static Bag decorate(Bag bag) { 058 if (bag instanceof Unmodifiable) { 059 return bag; 060 } 061 return new UnmodifiableBag(bag); 062 } 063 064 //----------------------------------------------------------------------- 065 /** 066 * Constructor that wraps (not copies). 067 * 068 * @param bag the bag to decorate, must not be null 069 * @throws IllegalArgumentException if bag is null 070 */ 071 private UnmodifiableBag(Bag bag) { 072 super(bag); 073 } 074 075 //----------------------------------------------------------------------- 076 /** 077 * Write the collection out using a custom routine. 078 * 079 * @param out the output stream 080 * @throws IOException 081 */ 082 private void writeObject(ObjectOutputStream out) throws IOException { 083 out.defaultWriteObject(); 084 out.writeObject(collection); 085 } 086 087 /** 088 * Read the collection in using a custom routine. 089 * 090 * @param in the input stream 091 * @throws IOException 092 * @throws ClassNotFoundException 093 */ 094 private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { 095 in.defaultReadObject(); 096 collection = (Collection) in.readObject(); 097 } 098 099 //----------------------------------------------------------------------- 100 public Iterator iterator() { 101 return UnmodifiableIterator.decorate(getCollection().iterator()); 102 } 103 104 public boolean add(Object object) { 105 throw new UnsupportedOperationException(); 106 } 107 108 public boolean addAll(Collection coll) { 109 throw new UnsupportedOperationException(); 110 } 111 112 public void clear() { 113 throw new UnsupportedOperationException(); 114 } 115 116 public boolean remove(Object object) { 117 throw new UnsupportedOperationException(); 118 } 119 120 public boolean removeAll(Collection coll) { 121 throw new UnsupportedOperationException(); 122 } 123 124 public boolean retainAll(Collection coll) { 125 throw new UnsupportedOperationException(); 126 } 127 128 //----------------------------------------------------------------------- 129 public boolean add(Object object, int count) { 130 throw new UnsupportedOperationException(); 131 } 132 133 public boolean remove(Object object, int count) { 134 throw new UnsupportedOperationException(); 135 } 136 137 public Set uniqueSet() { 138 Set set = getBag().uniqueSet(); 139 return UnmodifiableSet.decorate(set); 140 } 141 142 }