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} 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 * Constructor that wraps (not copies). 067 * 068 * @param list the list to decorate, must not be null 069 * @throws NullPointerException if list is null 070 */ 071 @SuppressWarnings("unchecked") // safe to upcast 072 public UnmodifiableList(final List<? extends E> list) { 073 super((List<E>) list); 074 } 075 076 @Override 077 public void add(final int index, final E object) { 078 throw new UnsupportedOperationException(); 079 } 080 081 @Override 082 public boolean add(final Object object) { 083 throw new UnsupportedOperationException(); 084 } 085 086 @Override 087 public boolean addAll(final Collection<? extends E> coll) { 088 throw new UnsupportedOperationException(); 089 } 090 091 @Override 092 public boolean addAll(final int index, final Collection<? extends E> coll) { 093 throw new UnsupportedOperationException(); 094 } 095 096 @Override 097 public void clear() { 098 throw new UnsupportedOperationException(); 099 } 100 101 @Override 102 public Iterator<E> iterator() { 103 return UnmodifiableIterator.unmodifiableIterator(decorated().iterator()); 104 } 105 106 @Override 107 public ListIterator<E> listIterator() { 108 return UnmodifiableListIterator.unmodifiableListIterator(decorated().listIterator()); 109 } 110 111 @Override 112 public ListIterator<E> listIterator(final int index) { 113 return UnmodifiableListIterator.unmodifiableListIterator(decorated().listIterator(index)); 114 } 115 116 @Override 117 public E remove(final int index) { 118 throw new UnsupportedOperationException(); 119 } 120 121 @Override 122 public boolean remove(final Object object) { 123 throw new UnsupportedOperationException(); 124 } 125 126 @Override 127 public boolean removeAll(final Collection<?> coll) { 128 throw new UnsupportedOperationException(); 129 } 130 131 /** 132 * @since 4.4 133 */ 134 @Override 135 public boolean removeIf(final Predicate<? super E> filter) { 136 throw new UnsupportedOperationException(); 137 } 138 139 @Override 140 public boolean retainAll(final Collection<?> coll) { 141 throw new UnsupportedOperationException(); 142 } 143 144 @Override 145 public E set(final int index, final E object) { 146 throw new UnsupportedOperationException(); 147 } 148 149 @Override 150 public List<E> subList(final int fromIndex, final int toIndex) { 151 final List<E> sub = decorated().subList(fromIndex, toIndex); 152 return new UnmodifiableList<>(sub); 153 } 154 155}