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.Predicate; 022 import org.apache.commons.collections.SortedBag; 023 024 /** 025 * Decorates another <code>SortedBag</code> to validate that additions 026 * match a specified predicate. 027 * <p> 028 * This bag exists to provide validation for the decorated bag. 029 * It is normally created to decorate an empty bag. 030 * If an object cannot be added to the bag, an IllegalArgumentException is thrown. 031 * <p> 032 * One usage would be to ensure that no null entries are added to the bag. 033 * <pre>SortedBag bag = PredicatedSortedBag.decorate(new TreeBag(), NotNullPredicate.INSTANCE);</pre> 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 * @author Paul Jack 042 */ 043 public class PredicatedSortedBag 044 extends PredicatedBag implements SortedBag { 045 046 /** Serialization version */ 047 private static final long serialVersionUID = 3448581314086406616L; 048 049 /** 050 * Factory method to create a predicated (validating) bag. 051 * <p> 052 * If there are any elements already in the bag being decorated, they 053 * are validated. 054 * 055 * @param bag the bag to decorate, must not be null 056 * @param predicate the predicate to use for validation, must not be null 057 * @return a new predicated SortedBag 058 * @throws IllegalArgumentException if bag or predicate is null 059 * @throws IllegalArgumentException if the bag contains invalid elements 060 */ 061 public static SortedBag decorate(SortedBag bag, Predicate predicate) { 062 return new PredicatedSortedBag(bag, predicate); 063 } 064 065 //----------------------------------------------------------------------- 066 /** 067 * Constructor that wraps (not copies). 068 * <p> 069 * If there are any elements already in the bag being decorated, they 070 * are validated. 071 * 072 * @param bag the bag to decorate, must not be null 073 * @param predicate the predicate to use for validation, must not be null 074 * @throws IllegalArgumentException if bag or predicate is null 075 * @throws IllegalArgumentException if the bag contains invalid elements 076 */ 077 protected PredicatedSortedBag(SortedBag bag, Predicate predicate) { 078 super(bag, predicate); 079 } 080 081 /** 082 * Gets the decorated sorted bag. 083 * 084 * @return the decorated bag 085 */ 086 protected SortedBag getSortedBag() { 087 return (SortedBag) getCollection(); 088 } 089 090 //----------------------------------------------------------------------- 091 public Object first() { 092 return getSortedBag().first(); 093 } 094 095 public Object last() { 096 return getSortedBag().last(); 097 } 098 099 public Comparator comparator() { 100 return getSortedBag().comparator(); 101 } 102 103 }