/*
 * 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 java.util.function.Predicate;

import org.apache.commons.collections4.BoundedCollection;
import org.apache.commons.collections4.iterators.AbstractListIteratorDecorator;
import org.apache.commons.collections4.iterators.UnmodifiableIterator;

Decorates another List to fix the size preventing add/remove.

The add, remove, clear and retain operations are unsupported. The set method is allowed (as it doesn't change the list size).

NOTE: Modifying the decorated list directly would results in influencing the outcome of method calls on this object. For example, the bounds of this list would reflect a newly added object to the underlying list.

This class is Serializable from Commons Collections 3.1.

Type parameters:
  • <E> – the type of elements in this collection
Since:3.0
/** * Decorates another <code>List</code> to fix the size preventing add/remove. * <p> * The add, remove, clear and retain operations are unsupported. * The set method is allowed (as it doesn't change the list size). * </p> * <p> * NOTE: * Modifying the decorated list directly would results in influencing the outcome * of method calls on this object. For example, the bounds of this list would reflect * a newly added object to the underlying list. * </p> * <p> * This class is Serializable from Commons Collections 3.1. * </p> * * @param <E> the type of elements in this collection * @since 3.0 */
public class FixedSizeList<E> extends AbstractSerializableListDecorator<E> implements BoundedCollection<E> {
Serialization version
/** Serialization version */
private static final long serialVersionUID = -2218010673611160319L;
Factory method to create a fixed size 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 fixed size list
Since:4.0
/** * Factory method to create a fixed size list. * * @param <E> the type of the elements in the list * @param list the list to decorate, must not be null * @return a new fixed size list * @throws NullPointerException if list is null * @since 4.0 */
public static <E> FixedSizeList<E> fixedSizeList(final List<E> list) { return new FixedSizeList<>(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 */
protected FixedSizeList(final List<E> list) { super(list); } //----------------------------------------------------------------------- @Override public boolean add(final E object) { throw unsupportedOperationException(); } @Override public void add(final int index, final E object) { throw unsupportedOperationException(); } @Override public boolean addAll(final Collection<? extends E> coll) { throw unsupportedOperationException(); } @Override public boolean addAll(final int index, final Collection<? extends E> coll) { throw unsupportedOperationException(); } @Override public void clear() { throw unsupportedOperationException(); } @Override public E get(final int index) { return decorated().get(index); } @Override public int indexOf(final Object object) { return decorated().indexOf(object); } @Override public Iterator<E> iterator() { return UnmodifiableIterator.unmodifiableIterator(decorated().iterator()); } @Override public int lastIndexOf(final Object object) { return decorated().lastIndexOf(object); } @Override public ListIterator<E> listIterator() { return new FixedSizeListIterator(decorated().listIterator(0)); } @Override public ListIterator<E> listIterator(final int index) { return new FixedSizeListIterator(decorated().listIterator(index)); } @Override public E remove(final int index) { throw unsupportedOperationException(); } @Override public boolean remove(final Object object) { throw unsupportedOperationException(); }
Since:4.4
/** * @since 4.4 */
@Override public boolean removeIf(Predicate<? super E> filter) { throw unsupportedOperationException(); } @Override public boolean removeAll(final Collection<?> coll) { throw unsupportedOperationException(); } @Override public boolean retainAll(final Collection<?> coll) { throw unsupportedOperationException(); } @Override public E set(final int index, final E object) { return decorated().set(index, object); } @Override public List<E> subList(final int fromIndex, final int toIndex) { final List<E> sub = decorated().subList(fromIndex, toIndex); return new FixedSizeList<>(sub); }
List iterator that only permits changes via set()
/** * List iterator that only permits changes via set() */
private class FixedSizeListIterator extends AbstractListIteratorDecorator<E> { protected FixedSizeListIterator(final ListIterator<E> iterator) { super(iterator); } @Override public void remove() { throw unsupportedOperationException(); } @Override public void add(final Object object) { throw unsupportedOperationException(); } } @Override public boolean isFull() { return true; } @Override public int maxSize() { return size(); } private static UnsupportedOperationException unsupportedOperationException() { return new UnsupportedOperationException("List is fixed size"); } }