/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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package org.apache.commons.collections4.list;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

import org.apache.commons.collections4.Unmodifiable;
import org.apache.commons.collections4.iterators.UnmodifiableIterator;
import org.apache.commons.collections4.iterators.UnmodifiableListIterator;

Decorates another List to ensure it can't be altered.

This class is Serializable from Commons Collections 3.1.

Attempts to modify it will result in an UnsupportedOperationException.

Since:3.0
/** * Decorates another <code>List</code> to ensure it can't be altered. * <p> * This class is Serializable from Commons Collections 3.1. * <p> * Attempts to modify it will result in an UnsupportedOperationException. * * @since 3.0 */
public final class UnmodifiableList<E> extends AbstractSerializableListDecorator<E> implements Unmodifiable {
Serialization version
/** Serialization version */
private static final long serialVersionUID = 6595182819922443652L;
Factory method to create an unmodifiable list.
Params:
  • list – the list to decorate, must not be null
Type parameters:
  • <E> – the type of the elements in the list
Throws:
Returns:a new unmodifiable list
Since:4.0
/** * Factory method to create an unmodifiable list. * * @param <E> the type of the elements in the list * @param list the list to decorate, must not be null * @return a new unmodifiable list * @throws NullPointerException if list is null * @since 4.0 */
public static <E> List<E> unmodifiableList(final List<? extends E> list) { if (list instanceof Unmodifiable) { @SuppressWarnings("unchecked") // safe to upcast final List<E> tmpList = (List<E>) list; return tmpList; } return new UnmodifiableList<>(list); } //-----------------------------------------------------------------------
Constructor that wraps (not copies).
Params:
  • list – the list to decorate, must not be null
Throws:
/** * Constructor that wraps (not copies). * * @param list the list to decorate, must not be null * @throws NullPointerException if list is null */
@SuppressWarnings("unchecked") // safe to upcast public UnmodifiableList(final List<? extends E> list) { super((List<E>) list); } //----------------------------------------------------------------------- @Override public Iterator<E> iterator() { return UnmodifiableIterator.unmodifiableIterator(decorated().iterator()); } @Override public boolean add(final Object object) { throw new UnsupportedOperationException(); } @Override public boolean addAll(final Collection<? extends E> coll) { throw new UnsupportedOperationException(); } @Override public void clear() { throw new UnsupportedOperationException(); } @Override public boolean remove(final Object object) { throw new UnsupportedOperationException(); } @Override public boolean removeAll(final Collection<?> coll) { throw new UnsupportedOperationException(); } @Override public boolean retainAll(final Collection<?> coll) { throw new UnsupportedOperationException(); } //----------------------------------------------------------------------- @Override public ListIterator<E> listIterator() { return UnmodifiableListIterator.umodifiableListIterator(decorated().listIterator()); } @Override public ListIterator<E> listIterator(final int index) { return UnmodifiableListIterator.umodifiableListIterator(decorated().listIterator(index)); } @Override public void add(final int index, final E object) { throw new UnsupportedOperationException(); } @Override public boolean addAll(final int index, final Collection<? extends E> coll) { throw new UnsupportedOperationException(); } @Override public E remove(final int index) { throw new UnsupportedOperationException(); } @Override public E set(final int index, final E object) { throw new UnsupportedOperationException(); } @Override public List<E> subList(final int fromIndex, final int toIndex) { final List<E> sub = decorated().subList(fromIndex, toIndex); return new UnmodifiableList<>(sub); } }