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 * @param <E> the type of the elements in the list. 039 * @since 3.0 040 */ 041public final class UnmodifiableList<E> 042 extends AbstractSerializableListDecorator<E> 043 implements Unmodifiable { 044 045 /** Serialization version */ 046 private static final long serialVersionUID = 6595182819922443652L; 047 048 /** 049 * Factory method to create an unmodifiable list. 050 * 051 * @param <E> the type of the elements in the list 052 * @param list the list to decorate, must not be null 053 * @return a new unmodifiable list 054 * @throws NullPointerException if list is null 055 * @since 4.0 056 */ 057 public static <E> List<E> unmodifiableList(final List<? extends E> list) { 058 if (list instanceof Unmodifiable) { 059 @SuppressWarnings("unchecked") // safe to upcast 060 final List<E> tmpList = (List<E>) list; 061 return tmpList; 062 } 063 return new UnmodifiableList<>(list); 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 @Override 078 public void add(final int index, final E object) { 079 throw new UnsupportedOperationException(); 080 } 081 082 @Override 083 public boolean add(final Object object) { 084 throw new UnsupportedOperationException(); 085 } 086 087 @Override 088 public boolean addAll(final Collection<? extends E> coll) { 089 throw new UnsupportedOperationException(); 090 } 091 092 @Override 093 public boolean addAll(final int index, final Collection<? extends E> coll) { 094 throw new UnsupportedOperationException(); 095 } 096 097 @Override 098 public void clear() { 099 throw new UnsupportedOperationException(); 100 } 101 102 @Override 103 public Iterator<E> iterator() { 104 return UnmodifiableIterator.unmodifiableIterator(decorated().iterator()); 105 } 106 107 @Override 108 public ListIterator<E> listIterator() { 109 return UnmodifiableListIterator.unmodifiableListIterator(decorated().listIterator()); 110 } 111 112 @Override 113 public ListIterator<E> listIterator(final int index) { 114 return UnmodifiableListIterator.unmodifiableListIterator(decorated().listIterator(index)); 115 } 116 117 @Override 118 public E remove(final int index) { 119 throw new UnsupportedOperationException(); 120 } 121 122 @Override 123 public boolean remove(final Object object) { 124 throw new UnsupportedOperationException(); 125 } 126 127 @Override 128 public boolean removeAll(final Collection<?> coll) { 129 throw new UnsupportedOperationException(); 130 } 131 132 /** 133 * @since 4.4 134 */ 135 @Override 136 public boolean removeIf(final Predicate<? super E> filter) { 137 throw new UnsupportedOperationException(); 138 } 139 140 @Override 141 public boolean retainAll(final Collection<?> coll) { 142 throw new UnsupportedOperationException(); 143 } 144 145 @Override 146 public E set(final int index, final E object) { 147 throw new UnsupportedOperationException(); 148 } 149 150 @Override 151 public List<E> subList(final int fromIndex, final int toIndex) { 152 final List<E> sub = decorated().subList(fromIndex, toIndex); 153 return new UnmodifiableList<>(sub); 154 } 155 156}