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 */ 017package org.apache.commons.collections4.list; 018 019import java.util.Collection; 020import java.util.List; 021import java.util.ListIterator; 022 023import org.apache.commons.collections4.Predicate; 024import org.apache.commons.collections4.collection.PredicatedCollection; 025import org.apache.commons.collections4.iterators.AbstractListIteratorDecorator; 026 027/** 028 * Decorates another <code>List</code> to validate that all additions 029 * match a specified predicate. 030 * <p> 031 * This list exists to provide validation for the decorated list. 032 * It is normally created to decorate an empty list. 033 * If an object cannot be added to the list, an IllegalArgumentException is thrown. 034 * </p> 035 * <p> 036 * One usage would be to ensure that no null entries are added to the list. 037 * </p> 038 * <pre> 039 * {@code 040 * List<String> list = 041 * PredicatedList.predicatedList(new ArrayList<String>(), PredicateUtils.notNullPredicate()); 042 * } 043 * </pre> 044 * <p> 045 * This class is Serializable from Commons Collections 3.1. 046 * </p> 047 * 048 * @since 3.0 049 */ 050public class PredicatedList<E> extends PredicatedCollection<E> implements List<E> { 051 052 /** Serialization version */ 053 private static final long serialVersionUID = -5722039223898659102L; 054 055 /** 056 * Factory method to create a predicated (validating) list. 057 * <p> 058 * If there are any elements already in the list being decorated, they 059 * are validated. 060 * 061 * @param <T> the type of the elements in the list 062 * @param list the list to decorate, must not be null 063 * @param predicate the predicate to use for validation, must not be null 064 * @return a new predicated list 065 * @throws NullPointerException if list or predicate is null 066 * @throws IllegalArgumentException if the list contains invalid elements 067 * @since 4.0 068 */ 069 public static <T> PredicatedList<T> predicatedList(final List<T> list, final Predicate<? super T> predicate) { 070 return new PredicatedList<>(list, predicate); 071 } 072 073 //----------------------------------------------------------------------- 074 /** 075 * Constructor that wraps (not copies). 076 * <p> 077 * If there are any elements already in the list being decorated, they 078 * are validated. 079 * 080 * @param list the list to decorate, must not be null 081 * @param predicate the predicate to use for validation, must not be null 082 * @throws NullPointerException if list or predicate is null 083 * @throws IllegalArgumentException if the list contains invalid elements 084 */ 085 protected PredicatedList(final List<E> list, final Predicate<? super E> predicate) { 086 super(list, predicate); 087 } 088 089 /** 090 * Gets the list being decorated. 091 * 092 * @return the decorated list 093 */ 094 @Override 095 protected List<E> decorated() { 096 return (List<E>) super.decorated(); 097 } 098 099 @Override 100 public boolean equals(final Object object) { 101 return object == this || decorated().equals(object); 102 } 103 104 @Override 105 public int hashCode() { 106 return decorated().hashCode(); 107 } 108 109 //----------------------------------------------------------------------- 110 111 @Override 112 public E get(final int index) { 113 return decorated().get(index); 114 } 115 116 @Override 117 public int indexOf(final Object object) { 118 return decorated().indexOf(object); 119 } 120 121 @Override 122 public int lastIndexOf(final Object object) { 123 return decorated().lastIndexOf(object); 124 } 125 126 @Override 127 public E remove(final int index) { 128 return decorated().remove(index); 129 } 130 131 //----------------------------------------------------------------------- 132 133 @Override 134 public void add(final int index, final E object) { 135 validate(object); 136 decorated().add(index, object); 137 } 138 139 @Override 140 public boolean addAll(final int index, final Collection<? extends E> coll) { 141 for (final E aColl : coll) { 142 validate(aColl); 143 } 144 return decorated().addAll(index, coll); 145 } 146 147 @Override 148 public ListIterator<E> listIterator() { 149 return listIterator(0); 150 } 151 152 @Override 153 public ListIterator<E> listIterator(final int i) { 154 return new PredicatedListIterator(decorated().listIterator(i)); 155 } 156 157 @Override 158 public E set(final int index, final E object) { 159 validate(object); 160 return decorated().set(index, object); 161 } 162 163 @Override 164 public List<E> subList(final int fromIndex, final int toIndex) { 165 final List<E> sub = decorated().subList(fromIndex, toIndex); 166 return new PredicatedList<>(sub, predicate); 167 } 168 169 /** 170 * Inner class Iterator for the PredicatedList 171 */ 172 protected class PredicatedListIterator extends AbstractListIteratorDecorator<E> { 173 174 /** 175 * Create a new predicated list iterator. 176 * 177 * @param iterator the list iterator to decorate 178 */ 179 protected PredicatedListIterator(final ListIterator<E> iterator) { 180 super(iterator); 181 } 182 183 @Override 184 public void add(final E object) { 185 validate(object); 186 getListIterator().add(object); 187 } 188 189 @Override 190 public void set(final E object) { 191 validate(object); 192 getListIterator().set(object); 193 } 194 } 195 196}