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 }