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.Iterator; 021import java.util.List; 022import java.util.ListIterator; 023import java.util.function.Predicate; 024 025import org.apache.commons.collections4.Unmodifiable; 026import org.apache.commons.collections4.iterators.UnmodifiableIterator; 027import org.apache.commons.collections4.iterators.UnmodifiableListIterator; 028 029/** 030 * Decorates another <code>List</code> to ensure it can't be altered. 031 * <p> 032 * This class is Serializable from Commons Collections 3.1. 033 * </p> 034 * <p> 035 * Attempts to modify it will result in an UnsupportedOperationException. 036 * </p> 037 * 038 * @since 3.0 039 */ 040public final class UnmodifiableList<E> 041 extends AbstractSerializableListDecorator<E> 042 implements Unmodifiable { 043 044 /** Serialization version */ 045 private static final long serialVersionUID = 6595182819922443652L; 046 047 /** 048 * Factory method to create an unmodifiable list. 049 * 050 * @param <E> the type of the elements in the list 051 * @param list the list to decorate, must not be null 052 * @return a new unmodifiable list 053 * @throws NullPointerException if list is null 054 * @since 4.0 055 */ 056 public static <E> List<E> unmodifiableList(final List<? extends E> list) { 057 if (list instanceof Unmodifiable) { 058 @SuppressWarnings("unchecked") // safe to upcast 059 final List<E> tmpList = (List<E>) list; 060 return tmpList; 061 } 062 return new UnmodifiableList<>(list); 063 } 064 065 //----------------------------------------------------------------------- 066 /** 067 * Constructor that wraps (not copies). 068 * 069 * @param list the list to decorate, must not be null 070 * @throws NullPointerException if list is null 071 */ 072 @SuppressWarnings("unchecked") // safe to upcast 073 public UnmodifiableList(final List<? extends E> list) { 074 super((List<E>) list); 075 } 076 077 //----------------------------------------------------------------------- 078 @Override 079 public Iterator<E> iterator() { 080 return UnmodifiableIterator.unmodifiableIterator(decorated().iterator()); 081 } 082 083 @Override 084 public boolean add(final Object object) { 085 throw new UnsupportedOperationException(); 086 } 087 088 @Override 089 public boolean addAll(final Collection<? extends E> coll) { 090 throw new UnsupportedOperationException(); 091 } 092 093 @Override 094 public void clear() { 095 throw new UnsupportedOperationException(); 096 } 097 098 @Override 099 public boolean remove(final Object object) { 100 throw new UnsupportedOperationException(); 101 } 102 103 /** 104 * @since 4.4 105 */ 106 @Override 107 public boolean removeIf(Predicate<? super E> filter) { 108 throw new UnsupportedOperationException(); 109 } 110 111 @Override 112 public boolean removeAll(final Collection<?> coll) { 113 throw new UnsupportedOperationException(); 114 } 115 116 @Override 117 public boolean retainAll(final Collection<?> coll) { 118 throw new UnsupportedOperationException(); 119 } 120 121 //----------------------------------------------------------------------- 122 @Override 123 public ListIterator<E> listIterator() { 124 return UnmodifiableListIterator.umodifiableListIterator(decorated().listIterator()); 125 } 126 127 @Override 128 public ListIterator<E> listIterator(final int index) { 129 return UnmodifiableListIterator.umodifiableListIterator(decorated().listIterator(index)); 130 } 131 132 @Override 133 public void add(final int index, final E object) { 134 throw new UnsupportedOperationException(); 135 } 136 137 @Override 138 public boolean addAll(final int index, final Collection<? extends E> coll) { 139 throw new UnsupportedOperationException(); 140 } 141 142 @Override 143 public E remove(final int index) { 144 throw new UnsupportedOperationException(); 145 } 146 147 @Override 148 public E set(final int index, final E object) { 149 throw new UnsupportedOperationException(); 150 } 151 152 @Override 153 public List<E> subList(final int fromIndex, final int toIndex) { 154 final List<E> sub = decorated().subList(fromIndex, toIndex); 155 return new UnmodifiableList<>(sub); 156 } 157 158}