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.util.Comparator;
020
021 import org.apache.commons.collections.SortedBag;
022 import org.apache.commons.collections.Transformer;
023
024 /**
025 * Decorates another <code>SortedBag</code> to transform objects that are added.
026 * <p>
027 * The add methods are affected by this class.
028 * Thus objects must be removed or searched for using their transformed form.
029 * For example, if the transformation converts Strings to Integers, you must
030 * use the Integer form to remove objects.
031 * <p>
032 * This class is Serializable from Commons Collections 3.1.
033 *
034 * @since Commons Collections 3.0
035 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
036 *
037 * @author Stephen Colebourne
038 */
039 public class TransformedSortedBag
040 extends TransformedBag implements SortedBag {
041
042 /** Serialization version */
043 private static final long serialVersionUID = -251737742649401930L;
044
045 /**
046 * Factory method to create a transforming sorted bag.
047 * <p>
048 * If there are any elements already in the bag being decorated, they
049 * are NOT transformed.
050 *
051 * @param bag the bag to decorate, must not be null
052 * @param transformer the transformer to use for conversion, must not be null
053 * @return a new transformed SortedBag
054 * @throws IllegalArgumentException if bag or transformer is null
055 */
056 public static SortedBag decorate(SortedBag bag, Transformer transformer) {
057 return new TransformedSortedBag(bag, transformer);
058 }
059
060 //-----------------------------------------------------------------------
061 /**
062 * Constructor that wraps (not copies).
063 * <p>
064 * If there are any elements already in the bag being decorated, they
065 * are NOT transformed.
066 *
067 * @param bag the bag to decorate, must not be null
068 * @param transformer the transformer to use for conversion, must not be null
069 * @throws IllegalArgumentException if bag or transformer is null
070 */
071 protected TransformedSortedBag(SortedBag bag, Transformer transformer) {
072 super(bag, transformer);
073 }
074
075 /**
076 * Gets the decorated bag.
077 *
078 * @return the decorated bag
079 */
080 protected SortedBag getSortedBag() {
081 return (SortedBag) collection;
082 }
083
084 //-----------------------------------------------------------------------
085 public Object first() {
086 return getSortedBag().first();
087 }
088
089 public Object last() {
090 return getSortedBag().last();
091 }
092
093 public Comparator comparator() {
094 return getSortedBag().comparator();
095 }
096
097 }