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 }