1.1 --- a/emul/compact/src/main/java/java/util/LinkedList.java Tue Feb 26 14:55:55 2013 +0100
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,1100 +0,0 @@
1.4 -/*
1.5 - * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
1.6 - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 - *
1.8 - * This code is free software; you can redistribute it and/or modify it
1.9 - * under the terms of the GNU General Public License version 2 only, as
1.10 - * published by the Free Software Foundation. Oracle designates this
1.11 - * particular file as subject to the "Classpath" exception as provided
1.12 - * by Oracle in the LICENSE file that accompanied this code.
1.13 - *
1.14 - * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 - * version 2 for more details (a copy is included in the LICENSE file that
1.18 - * accompanied this code).
1.19 - *
1.20 - * You should have received a copy of the GNU General Public License version
1.21 - * 2 along with this work; if not, write to the Free Software Foundation,
1.22 - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 - *
1.24 - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 - * or visit www.oracle.com if you need additional information or have any
1.26 - * questions.
1.27 - */
1.28 -
1.29 -package java.util;
1.30 -
1.31 -/**
1.32 - * Doubly-linked list implementation of the {@code List} and {@code Deque}
1.33 - * interfaces. Implements all optional list operations, and permits all
1.34 - * elements (including {@code null}).
1.35 - *
1.36 - * <p>All of the operations perform as could be expected for a doubly-linked
1.37 - * list. Operations that index into the list will traverse the list from
1.38 - * the beginning or the end, whichever is closer to the specified index.
1.39 - *
1.40 - * <p><strong>Note that this implementation is not synchronized.</strong>
1.41 - * If multiple threads access a linked list concurrently, and at least
1.42 - * one of the threads modifies the list structurally, it <i>must</i> be
1.43 - * synchronized externally. (A structural modification is any operation
1.44 - * that adds or deletes one or more elements; merely setting the value of
1.45 - * an element is not a structural modification.) This is typically
1.46 - * accomplished by synchronizing on some object that naturally
1.47 - * encapsulates the list.
1.48 - *
1.49 - * If no such object exists, the list should be "wrapped" using the
1.50 - * {@link Collections#synchronizedList Collections.synchronizedList}
1.51 - * method. This is best done at creation time, to prevent accidental
1.52 - * unsynchronized access to the list:<pre>
1.53 - * List list = Collections.synchronizedList(new LinkedList(...));</pre>
1.54 - *
1.55 - * <p>The iterators returned by this class's {@code iterator} and
1.56 - * {@code listIterator} methods are <i>fail-fast</i>: if the list is
1.57 - * structurally modified at any time after the iterator is created, in
1.58 - * any way except through the Iterator's own {@code remove} or
1.59 - * {@code add} methods, the iterator will throw a {@link
1.60 - * ConcurrentModificationException}. Thus, in the face of concurrent
1.61 - * modification, the iterator fails quickly and cleanly, rather than
1.62 - * risking arbitrary, non-deterministic behavior at an undetermined
1.63 - * time in the future.
1.64 - *
1.65 - * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
1.66 - * as it is, generally speaking, impossible to make any hard guarantees in the
1.67 - * presence of unsynchronized concurrent modification. Fail-fast iterators
1.68 - * throw {@code ConcurrentModificationException} on a best-effort basis.
1.69 - * Therefore, it would be wrong to write a program that depended on this
1.70 - * exception for its correctness: <i>the fail-fast behavior of iterators
1.71 - * should be used only to detect bugs.</i>
1.72 - *
1.73 - * <p>This class is a member of the
1.74 - * <a href="{@docRoot}/../technotes/guides/collections/index.html">
1.75 - * Java Collections Framework</a>.
1.76 - *
1.77 - * @author Josh Bloch
1.78 - * @see List
1.79 - * @see ArrayList
1.80 - * @since 1.2
1.81 - * @param <E> the type of elements held in this collection
1.82 - */
1.83 -
1.84 -public class LinkedList<E>
1.85 - extends AbstractSequentialList<E>
1.86 - implements List<E>, Deque<E>, Cloneable, java.io.Serializable
1.87 -{
1.88 - transient int size = 0;
1.89 -
1.90 - /**
1.91 - * Pointer to first node.
1.92 - * Invariant: (first == null && last == null) ||
1.93 - * (first.prev == null && first.item != null)
1.94 - */
1.95 - transient Node<E> first;
1.96 -
1.97 - /**
1.98 - * Pointer to last node.
1.99 - * Invariant: (first == null && last == null) ||
1.100 - * (last.next == null && last.item != null)
1.101 - */
1.102 - transient Node<E> last;
1.103 -
1.104 - /**
1.105 - * Constructs an empty list.
1.106 - */
1.107 - public LinkedList() {
1.108 - }
1.109 -
1.110 - /**
1.111 - * Constructs a list containing the elements of the specified
1.112 - * collection, in the order they are returned by the collection's
1.113 - * iterator.
1.114 - *
1.115 - * @param c the collection whose elements are to be placed into this list
1.116 - * @throws NullPointerException if the specified collection is null
1.117 - */
1.118 - public LinkedList(Collection<? extends E> c) {
1.119 - this();
1.120 - addAll(c);
1.121 - }
1.122 -
1.123 - /**
1.124 - * Links e as first element.
1.125 - */
1.126 - private void linkFirst(E e) {
1.127 - final Node<E> f = first;
1.128 - final Node<E> newNode = new Node<>(null, e, f);
1.129 - first = newNode;
1.130 - if (f == null)
1.131 - last = newNode;
1.132 - else
1.133 - f.prev = newNode;
1.134 - size++;
1.135 - modCount++;
1.136 - }
1.137 -
1.138 - /**
1.139 - * Links e as last element.
1.140 - */
1.141 - void linkLast(E e) {
1.142 - final Node<E> l = last;
1.143 - final Node<E> newNode = new Node<>(l, e, null);
1.144 - last = newNode;
1.145 - if (l == null)
1.146 - first = newNode;
1.147 - else
1.148 - l.next = newNode;
1.149 - size++;
1.150 - modCount++;
1.151 - }
1.152 -
1.153 - /**
1.154 - * Inserts element e before non-null Node succ.
1.155 - */
1.156 - void linkBefore(E e, Node<E> succ) {
1.157 - // assert succ != null;
1.158 - final Node<E> pred = succ.prev;
1.159 - final Node<E> newNode = new Node<>(pred, e, succ);
1.160 - succ.prev = newNode;
1.161 - if (pred == null)
1.162 - first = newNode;
1.163 - else
1.164 - pred.next = newNode;
1.165 - size++;
1.166 - modCount++;
1.167 - }
1.168 -
1.169 - /**
1.170 - * Unlinks non-null first node f.
1.171 - */
1.172 - private E unlinkFirst(Node<E> f) {
1.173 - // assert f == first && f != null;
1.174 - final E element = f.item;
1.175 - final Node<E> next = f.next;
1.176 - f.item = null;
1.177 - f.next = null; // help GC
1.178 - first = next;
1.179 - if (next == null)
1.180 - last = null;
1.181 - else
1.182 - next.prev = null;
1.183 - size--;
1.184 - modCount++;
1.185 - return element;
1.186 - }
1.187 -
1.188 - /**
1.189 - * Unlinks non-null last node l.
1.190 - */
1.191 - private E unlinkLast(Node<E> l) {
1.192 - // assert l == last && l != null;
1.193 - final E element = l.item;
1.194 - final Node<E> prev = l.prev;
1.195 - l.item = null;
1.196 - l.prev = null; // help GC
1.197 - last = prev;
1.198 - if (prev == null)
1.199 - first = null;
1.200 - else
1.201 - prev.next = null;
1.202 - size--;
1.203 - modCount++;
1.204 - return element;
1.205 - }
1.206 -
1.207 - /**
1.208 - * Unlinks non-null node x.
1.209 - */
1.210 - E unlink(Node<E> x) {
1.211 - // assert x != null;
1.212 - final E element = x.item;
1.213 - final Node<E> next = x.next;
1.214 - final Node<E> prev = x.prev;
1.215 -
1.216 - if (prev == null) {
1.217 - first = next;
1.218 - } else {
1.219 - prev.next = next;
1.220 - x.prev = null;
1.221 - }
1.222 -
1.223 - if (next == null) {
1.224 - last = prev;
1.225 - } else {
1.226 - next.prev = prev;
1.227 - x.next = null;
1.228 - }
1.229 -
1.230 - x.item = null;
1.231 - size--;
1.232 - modCount++;
1.233 - return element;
1.234 - }
1.235 -
1.236 - /**
1.237 - * Returns the first element in this list.
1.238 - *
1.239 - * @return the first element in this list
1.240 - * @throws NoSuchElementException if this list is empty
1.241 - */
1.242 - public E getFirst() {
1.243 - final Node<E> f = first;
1.244 - if (f == null)
1.245 - throw new NoSuchElementException();
1.246 - return f.item;
1.247 - }
1.248 -
1.249 - /**
1.250 - * Returns the last element in this list.
1.251 - *
1.252 - * @return the last element in this list
1.253 - * @throws NoSuchElementException if this list is empty
1.254 - */
1.255 - public E getLast() {
1.256 - final Node<E> l = last;
1.257 - if (l == null)
1.258 - throw new NoSuchElementException();
1.259 - return l.item;
1.260 - }
1.261 -
1.262 - /**
1.263 - * Removes and returns the first element from this list.
1.264 - *
1.265 - * @return the first element from this list
1.266 - * @throws NoSuchElementException if this list is empty
1.267 - */
1.268 - public E removeFirst() {
1.269 - final Node<E> f = first;
1.270 - if (f == null)
1.271 - throw new NoSuchElementException();
1.272 - return unlinkFirst(f);
1.273 - }
1.274 -
1.275 - /**
1.276 - * Removes and returns the last element from this list.
1.277 - *
1.278 - * @return the last element from this list
1.279 - * @throws NoSuchElementException if this list is empty
1.280 - */
1.281 - public E removeLast() {
1.282 - final Node<E> l = last;
1.283 - if (l == null)
1.284 - throw new NoSuchElementException();
1.285 - return unlinkLast(l);
1.286 - }
1.287 -
1.288 - /**
1.289 - * Inserts the specified element at the beginning of this list.
1.290 - *
1.291 - * @param e the element to add
1.292 - */
1.293 - public void addFirst(E e) {
1.294 - linkFirst(e);
1.295 - }
1.296 -
1.297 - /**
1.298 - * Appends the specified element to the end of this list.
1.299 - *
1.300 - * <p>This method is equivalent to {@link #add}.
1.301 - *
1.302 - * @param e the element to add
1.303 - */
1.304 - public void addLast(E e) {
1.305 - linkLast(e);
1.306 - }
1.307 -
1.308 - /**
1.309 - * Returns {@code true} if this list contains the specified element.
1.310 - * More formally, returns {@code true} if and only if this list contains
1.311 - * at least one element {@code e} such that
1.312 - * <tt>(o==null ? e==null : o.equals(e))</tt>.
1.313 - *
1.314 - * @param o element whose presence in this list is to be tested
1.315 - * @return {@code true} if this list contains the specified element
1.316 - */
1.317 - public boolean contains(Object o) {
1.318 - return indexOf(o) != -1;
1.319 - }
1.320 -
1.321 - /**
1.322 - * Returns the number of elements in this list.
1.323 - *
1.324 - * @return the number of elements in this list
1.325 - */
1.326 - public int size() {
1.327 - return size;
1.328 - }
1.329 -
1.330 - /**
1.331 - * Appends the specified element to the end of this list.
1.332 - *
1.333 - * <p>This method is equivalent to {@link #addLast}.
1.334 - *
1.335 - * @param e element to be appended to this list
1.336 - * @return {@code true} (as specified by {@link Collection#add})
1.337 - */
1.338 - public boolean add(E e) {
1.339 - linkLast(e);
1.340 - return true;
1.341 - }
1.342 -
1.343 - /**
1.344 - * Removes the first occurrence of the specified element from this list,
1.345 - * if it is present. If this list does not contain the element, it is
1.346 - * unchanged. More formally, removes the element with the lowest index
1.347 - * {@code i} such that
1.348 - * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>
1.349 - * (if such an element exists). Returns {@code true} if this list
1.350 - * contained the specified element (or equivalently, if this list
1.351 - * changed as a result of the call).
1.352 - *
1.353 - * @param o element to be removed from this list, if present
1.354 - * @return {@code true} if this list contained the specified element
1.355 - */
1.356 - public boolean remove(Object o) {
1.357 - if (o == null) {
1.358 - for (Node<E> x = first; x != null; x = x.next) {
1.359 - if (x.item == null) {
1.360 - unlink(x);
1.361 - return true;
1.362 - }
1.363 - }
1.364 - } else {
1.365 - for (Node<E> x = first; x != null; x = x.next) {
1.366 - if (o.equals(x.item)) {
1.367 - unlink(x);
1.368 - return true;
1.369 - }
1.370 - }
1.371 - }
1.372 - return false;
1.373 - }
1.374 -
1.375 - /**
1.376 - * Appends all of the elements in the specified collection to the end of
1.377 - * this list, in the order that they are returned by the specified
1.378 - * collection's iterator. The behavior of this operation is undefined if
1.379 - * the specified collection is modified while the operation is in
1.380 - * progress. (Note that this will occur if the specified collection is
1.381 - * this list, and it's nonempty.)
1.382 - *
1.383 - * @param c collection containing elements to be added to this list
1.384 - * @return {@code true} if this list changed as a result of the call
1.385 - * @throws NullPointerException if the specified collection is null
1.386 - */
1.387 - public boolean addAll(Collection<? extends E> c) {
1.388 - return addAll(size, c);
1.389 - }
1.390 -
1.391 - /**
1.392 - * Inserts all of the elements in the specified collection into this
1.393 - * list, starting at the specified position. Shifts the element
1.394 - * currently at that position (if any) and any subsequent elements to
1.395 - * the right (increases their indices). The new elements will appear
1.396 - * in the list in the order that they are returned by the
1.397 - * specified collection's iterator.
1.398 - *
1.399 - * @param index index at which to insert the first element
1.400 - * from the specified collection
1.401 - * @param c collection containing elements to be added to this list
1.402 - * @return {@code true} if this list changed as a result of the call
1.403 - * @throws IndexOutOfBoundsException {@inheritDoc}
1.404 - * @throws NullPointerException if the specified collection is null
1.405 - */
1.406 - public boolean addAll(int index, Collection<? extends E> c) {
1.407 - checkPositionIndex(index);
1.408 -
1.409 - Object[] a = c.toArray();
1.410 - int numNew = a.length;
1.411 - if (numNew == 0)
1.412 - return false;
1.413 -
1.414 - Node<E> pred, succ;
1.415 - if (index == size) {
1.416 - succ = null;
1.417 - pred = last;
1.418 - } else {
1.419 - succ = node(index);
1.420 - pred = succ.prev;
1.421 - }
1.422 -
1.423 - for (Object o : a) {
1.424 - @SuppressWarnings("unchecked") E e = (E) o;
1.425 - Node<E> newNode = new Node<>(pred, e, null);
1.426 - if (pred == null)
1.427 - first = newNode;
1.428 - else
1.429 - pred.next = newNode;
1.430 - pred = newNode;
1.431 - }
1.432 -
1.433 - if (succ == null) {
1.434 - last = pred;
1.435 - } else {
1.436 - pred.next = succ;
1.437 - succ.prev = pred;
1.438 - }
1.439 -
1.440 - size += numNew;
1.441 - modCount++;
1.442 - return true;
1.443 - }
1.444 -
1.445 - /**
1.446 - * Removes all of the elements from this list.
1.447 - * The list will be empty after this call returns.
1.448 - */
1.449 - public void clear() {
1.450 - // Clearing all of the links between nodes is "unnecessary", but:
1.451 - // - helps a generational GC if the discarded nodes inhabit
1.452 - // more than one generation
1.453 - // - is sure to free memory even if there is a reachable Iterator
1.454 - for (Node<E> x = first; x != null; ) {
1.455 - Node<E> next = x.next;
1.456 - x.item = null;
1.457 - x.next = null;
1.458 - x.prev = null;
1.459 - x = next;
1.460 - }
1.461 - first = last = null;
1.462 - size = 0;
1.463 - modCount++;
1.464 - }
1.465 -
1.466 -
1.467 - // Positional Access Operations
1.468 -
1.469 - /**
1.470 - * Returns the element at the specified position in this list.
1.471 - *
1.472 - * @param index index of the element to return
1.473 - * @return the element at the specified position in this list
1.474 - * @throws IndexOutOfBoundsException {@inheritDoc}
1.475 - */
1.476 - public E get(int index) {
1.477 - checkElementIndex(index);
1.478 - return node(index).item;
1.479 - }
1.480 -
1.481 - /**
1.482 - * Replaces the element at the specified position in this list with the
1.483 - * specified element.
1.484 - *
1.485 - * @param index index of the element to replace
1.486 - * @param element element to be stored at the specified position
1.487 - * @return the element previously at the specified position
1.488 - * @throws IndexOutOfBoundsException {@inheritDoc}
1.489 - */
1.490 - public E set(int index, E element) {
1.491 - checkElementIndex(index);
1.492 - Node<E> x = node(index);
1.493 - E oldVal = x.item;
1.494 - x.item = element;
1.495 - return oldVal;
1.496 - }
1.497 -
1.498 - /**
1.499 - * Inserts the specified element at the specified position in this list.
1.500 - * Shifts the element currently at that position (if any) and any
1.501 - * subsequent elements to the right (adds one to their indices).
1.502 - *
1.503 - * @param index index at which the specified element is to be inserted
1.504 - * @param element element to be inserted
1.505 - * @throws IndexOutOfBoundsException {@inheritDoc}
1.506 - */
1.507 - public void add(int index, E element) {
1.508 - checkPositionIndex(index);
1.509 -
1.510 - if (index == size)
1.511 - linkLast(element);
1.512 - else
1.513 - linkBefore(element, node(index));
1.514 - }
1.515 -
1.516 - /**
1.517 - * Removes the element at the specified position in this list. Shifts any
1.518 - * subsequent elements to the left (subtracts one from their indices).
1.519 - * Returns the element that was removed from the list.
1.520 - *
1.521 - * @param index the index of the element to be removed
1.522 - * @return the element previously at the specified position
1.523 - * @throws IndexOutOfBoundsException {@inheritDoc}
1.524 - */
1.525 - public E remove(int index) {
1.526 - checkElementIndex(index);
1.527 - return unlink(node(index));
1.528 - }
1.529 -
1.530 - /**
1.531 - * Tells if the argument is the index of an existing element.
1.532 - */
1.533 - private boolean isElementIndex(int index) {
1.534 - return index >= 0 && index < size;
1.535 - }
1.536 -
1.537 - /**
1.538 - * Tells if the argument is the index of a valid position for an
1.539 - * iterator or an add operation.
1.540 - */
1.541 - private boolean isPositionIndex(int index) {
1.542 - return index >= 0 && index <= size;
1.543 - }
1.544 -
1.545 - /**
1.546 - * Constructs an IndexOutOfBoundsException detail message.
1.547 - * Of the many possible refactorings of the error handling code,
1.548 - * this "outlining" performs best with both server and client VMs.
1.549 - */
1.550 - private String outOfBoundsMsg(int index) {
1.551 - return "Index: "+index+", Size: "+size;
1.552 - }
1.553 -
1.554 - private void checkElementIndex(int index) {
1.555 - if (!isElementIndex(index))
1.556 - throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1.557 - }
1.558 -
1.559 - private void checkPositionIndex(int index) {
1.560 - if (!isPositionIndex(index))
1.561 - throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
1.562 - }
1.563 -
1.564 - /**
1.565 - * Returns the (non-null) Node at the specified element index.
1.566 - */
1.567 - Node<E> node(int index) {
1.568 - // assert isElementIndex(index);
1.569 -
1.570 - if (index < (size >> 1)) {
1.571 - Node<E> x = first;
1.572 - for (int i = 0; i < index; i++)
1.573 - x = x.next;
1.574 - return x;
1.575 - } else {
1.576 - Node<E> x = last;
1.577 - for (int i = size - 1; i > index; i--)
1.578 - x = x.prev;
1.579 - return x;
1.580 - }
1.581 - }
1.582 -
1.583 - // Search Operations
1.584 -
1.585 - /**
1.586 - * Returns the index of the first occurrence of the specified element
1.587 - * in this list, or -1 if this list does not contain the element.
1.588 - * More formally, returns the lowest index {@code i} such that
1.589 - * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
1.590 - * or -1 if there is no such index.
1.591 - *
1.592 - * @param o element to search for
1.593 - * @return the index of the first occurrence of the specified element in
1.594 - * this list, or -1 if this list does not contain the element
1.595 - */
1.596 - public int indexOf(Object o) {
1.597 - int index = 0;
1.598 - if (o == null) {
1.599 - for (Node<E> x = first; x != null; x = x.next) {
1.600 - if (x.item == null)
1.601 - return index;
1.602 - index++;
1.603 - }
1.604 - } else {
1.605 - for (Node<E> x = first; x != null; x = x.next) {
1.606 - if (o.equals(x.item))
1.607 - return index;
1.608 - index++;
1.609 - }
1.610 - }
1.611 - return -1;
1.612 - }
1.613 -
1.614 - /**
1.615 - * Returns the index of the last occurrence of the specified element
1.616 - * in this list, or -1 if this list does not contain the element.
1.617 - * More formally, returns the highest index {@code i} such that
1.618 - * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
1.619 - * or -1 if there is no such index.
1.620 - *
1.621 - * @param o element to search for
1.622 - * @return the index of the last occurrence of the specified element in
1.623 - * this list, or -1 if this list does not contain the element
1.624 - */
1.625 - public int lastIndexOf(Object o) {
1.626 - int index = size;
1.627 - if (o == null) {
1.628 - for (Node<E> x = last; x != null; x = x.prev) {
1.629 - index--;
1.630 - if (x.item == null)
1.631 - return index;
1.632 - }
1.633 - } else {
1.634 - for (Node<E> x = last; x != null; x = x.prev) {
1.635 - index--;
1.636 - if (o.equals(x.item))
1.637 - return index;
1.638 - }
1.639 - }
1.640 - return -1;
1.641 - }
1.642 -
1.643 - // Queue operations.
1.644 -
1.645 - /**
1.646 - * Retrieves, but does not remove, the head (first element) of this list.
1.647 - *
1.648 - * @return the head of this list, or {@code null} if this list is empty
1.649 - * @since 1.5
1.650 - */
1.651 - public E peek() {
1.652 - final Node<E> f = first;
1.653 - return (f == null) ? null : f.item;
1.654 - }
1.655 -
1.656 - /**
1.657 - * Retrieves, but does not remove, the head (first element) of this list.
1.658 - *
1.659 - * @return the head of this list
1.660 - * @throws NoSuchElementException if this list is empty
1.661 - * @since 1.5
1.662 - */
1.663 - public E element() {
1.664 - return getFirst();
1.665 - }
1.666 -
1.667 - /**
1.668 - * Retrieves and removes the head (first element) of this list.
1.669 - *
1.670 - * @return the head of this list, or {@code null} if this list is empty
1.671 - * @since 1.5
1.672 - */
1.673 - public E poll() {
1.674 - final Node<E> f = first;
1.675 - return (f == null) ? null : unlinkFirst(f);
1.676 - }
1.677 -
1.678 - /**
1.679 - * Retrieves and removes the head (first element) of this list.
1.680 - *
1.681 - * @return the head of this list
1.682 - * @throws NoSuchElementException if this list is empty
1.683 - * @since 1.5
1.684 - */
1.685 - public E remove() {
1.686 - return removeFirst();
1.687 - }
1.688 -
1.689 - /**
1.690 - * Adds the specified element as the tail (last element) of this list.
1.691 - *
1.692 - * @param e the element to add
1.693 - * @return {@code true} (as specified by {@link Queue#offer})
1.694 - * @since 1.5
1.695 - */
1.696 - public boolean offer(E e) {
1.697 - return add(e);
1.698 - }
1.699 -
1.700 - // Deque operations
1.701 - /**
1.702 - * Inserts the specified element at the front of this list.
1.703 - *
1.704 - * @param e the element to insert
1.705 - * @return {@code true} (as specified by {@link Deque#offerFirst})
1.706 - * @since 1.6
1.707 - */
1.708 - public boolean offerFirst(E e) {
1.709 - addFirst(e);
1.710 - return true;
1.711 - }
1.712 -
1.713 - /**
1.714 - * Inserts the specified element at the end of this list.
1.715 - *
1.716 - * @param e the element to insert
1.717 - * @return {@code true} (as specified by {@link Deque#offerLast})
1.718 - * @since 1.6
1.719 - */
1.720 - public boolean offerLast(E e) {
1.721 - addLast(e);
1.722 - return true;
1.723 - }
1.724 -
1.725 - /**
1.726 - * Retrieves, but does not remove, the first element of this list,
1.727 - * or returns {@code null} if this list is empty.
1.728 - *
1.729 - * @return the first element of this list, or {@code null}
1.730 - * if this list is empty
1.731 - * @since 1.6
1.732 - */
1.733 - public E peekFirst() {
1.734 - final Node<E> f = first;
1.735 - return (f == null) ? null : f.item;
1.736 - }
1.737 -
1.738 - /**
1.739 - * Retrieves, but does not remove, the last element of this list,
1.740 - * or returns {@code null} if this list is empty.
1.741 - *
1.742 - * @return the last element of this list, or {@code null}
1.743 - * if this list is empty
1.744 - * @since 1.6
1.745 - */
1.746 - public E peekLast() {
1.747 - final Node<E> l = last;
1.748 - return (l == null) ? null : l.item;
1.749 - }
1.750 -
1.751 - /**
1.752 - * Retrieves and removes the first element of this list,
1.753 - * or returns {@code null} if this list is empty.
1.754 - *
1.755 - * @return the first element of this list, or {@code null} if
1.756 - * this list is empty
1.757 - * @since 1.6
1.758 - */
1.759 - public E pollFirst() {
1.760 - final Node<E> f = first;
1.761 - return (f == null) ? null : unlinkFirst(f);
1.762 - }
1.763 -
1.764 - /**
1.765 - * Retrieves and removes the last element of this list,
1.766 - * or returns {@code null} if this list is empty.
1.767 - *
1.768 - * @return the last element of this list, or {@code null} if
1.769 - * this list is empty
1.770 - * @since 1.6
1.771 - */
1.772 - public E pollLast() {
1.773 - final Node<E> l = last;
1.774 - return (l == null) ? null : unlinkLast(l);
1.775 - }
1.776 -
1.777 - /**
1.778 - * Pushes an element onto the stack represented by this list. In other
1.779 - * words, inserts the element at the front of this list.
1.780 - *
1.781 - * <p>This method is equivalent to {@link #addFirst}.
1.782 - *
1.783 - * @param e the element to push
1.784 - * @since 1.6
1.785 - */
1.786 - public void push(E e) {
1.787 - addFirst(e);
1.788 - }
1.789 -
1.790 - /**
1.791 - * Pops an element from the stack represented by this list. In other
1.792 - * words, removes and returns the first element of this list.
1.793 - *
1.794 - * <p>This method is equivalent to {@link #removeFirst()}.
1.795 - *
1.796 - * @return the element at the front of this list (which is the top
1.797 - * of the stack represented by this list)
1.798 - * @throws NoSuchElementException if this list is empty
1.799 - * @since 1.6
1.800 - */
1.801 - public E pop() {
1.802 - return removeFirst();
1.803 - }
1.804 -
1.805 - /**
1.806 - * Removes the first occurrence of the specified element in this
1.807 - * list (when traversing the list from head to tail). If the list
1.808 - * does not contain the element, it is unchanged.
1.809 - *
1.810 - * @param o element to be removed from this list, if present
1.811 - * @return {@code true} if the list contained the specified element
1.812 - * @since 1.6
1.813 - */
1.814 - public boolean removeFirstOccurrence(Object o) {
1.815 - return remove(o);
1.816 - }
1.817 -
1.818 - /**
1.819 - * Removes the last occurrence of the specified element in this
1.820 - * list (when traversing the list from head to tail). If the list
1.821 - * does not contain the element, it is unchanged.
1.822 - *
1.823 - * @param o element to be removed from this list, if present
1.824 - * @return {@code true} if the list contained the specified element
1.825 - * @since 1.6
1.826 - */
1.827 - public boolean removeLastOccurrence(Object o) {
1.828 - if (o == null) {
1.829 - for (Node<E> x = last; x != null; x = x.prev) {
1.830 - if (x.item == null) {
1.831 - unlink(x);
1.832 - return true;
1.833 - }
1.834 - }
1.835 - } else {
1.836 - for (Node<E> x = last; x != null; x = x.prev) {
1.837 - if (o.equals(x.item)) {
1.838 - unlink(x);
1.839 - return true;
1.840 - }
1.841 - }
1.842 - }
1.843 - return false;
1.844 - }
1.845 -
1.846 - /**
1.847 - * Returns a list-iterator of the elements in this list (in proper
1.848 - * sequence), starting at the specified position in the list.
1.849 - * Obeys the general contract of {@code List.listIterator(int)}.<p>
1.850 - *
1.851 - * The list-iterator is <i>fail-fast</i>: if the list is structurally
1.852 - * modified at any time after the Iterator is created, in any way except
1.853 - * through the list-iterator's own {@code remove} or {@code add}
1.854 - * methods, the list-iterator will throw a
1.855 - * {@code ConcurrentModificationException}. Thus, in the face of
1.856 - * concurrent modification, the iterator fails quickly and cleanly, rather
1.857 - * than risking arbitrary, non-deterministic behavior at an undetermined
1.858 - * time in the future.
1.859 - *
1.860 - * @param index index of the first element to be returned from the
1.861 - * list-iterator (by a call to {@code next})
1.862 - * @return a ListIterator of the elements in this list (in proper
1.863 - * sequence), starting at the specified position in the list
1.864 - * @throws IndexOutOfBoundsException {@inheritDoc}
1.865 - * @see List#listIterator(int)
1.866 - */
1.867 - public ListIterator<E> listIterator(int index) {
1.868 - checkPositionIndex(index);
1.869 - return new ListItr(index);
1.870 - }
1.871 -
1.872 - private class ListItr implements ListIterator<E> {
1.873 - private Node<E> lastReturned = null;
1.874 - private Node<E> next;
1.875 - private int nextIndex;
1.876 - private int expectedModCount = modCount;
1.877 -
1.878 - ListItr(int index) {
1.879 - // assert isPositionIndex(index);
1.880 - next = (index == size) ? null : node(index);
1.881 - nextIndex = index;
1.882 - }
1.883 -
1.884 - public boolean hasNext() {
1.885 - return nextIndex < size;
1.886 - }
1.887 -
1.888 - public E next() {
1.889 - checkForComodification();
1.890 - if (!hasNext())
1.891 - throw new NoSuchElementException();
1.892 -
1.893 - lastReturned = next;
1.894 - next = next.next;
1.895 - nextIndex++;
1.896 - return lastReturned.item;
1.897 - }
1.898 -
1.899 - public boolean hasPrevious() {
1.900 - return nextIndex > 0;
1.901 - }
1.902 -
1.903 - public E previous() {
1.904 - checkForComodification();
1.905 - if (!hasPrevious())
1.906 - throw new NoSuchElementException();
1.907 -
1.908 - lastReturned = next = (next == null) ? last : next.prev;
1.909 - nextIndex--;
1.910 - return lastReturned.item;
1.911 - }
1.912 -
1.913 - public int nextIndex() {
1.914 - return nextIndex;
1.915 - }
1.916 -
1.917 - public int previousIndex() {
1.918 - return nextIndex - 1;
1.919 - }
1.920 -
1.921 - public void remove() {
1.922 - checkForComodification();
1.923 - if (lastReturned == null)
1.924 - throw new IllegalStateException();
1.925 -
1.926 - Node<E> lastNext = lastReturned.next;
1.927 - unlink(lastReturned);
1.928 - if (next == lastReturned)
1.929 - next = lastNext;
1.930 - else
1.931 - nextIndex--;
1.932 - lastReturned = null;
1.933 - expectedModCount++;
1.934 - }
1.935 -
1.936 - public void set(E e) {
1.937 - if (lastReturned == null)
1.938 - throw new IllegalStateException();
1.939 - checkForComodification();
1.940 - lastReturned.item = e;
1.941 - }
1.942 -
1.943 - public void add(E e) {
1.944 - checkForComodification();
1.945 - lastReturned = null;
1.946 - if (next == null)
1.947 - linkLast(e);
1.948 - else
1.949 - linkBefore(e, next);
1.950 - nextIndex++;
1.951 - expectedModCount++;
1.952 - }
1.953 -
1.954 - final void checkForComodification() {
1.955 - if (modCount != expectedModCount)
1.956 - throw new ConcurrentModificationException();
1.957 - }
1.958 - }
1.959 -
1.960 - private static class Node<E> {
1.961 - E item;
1.962 - Node<E> next;
1.963 - Node<E> prev;
1.964 -
1.965 - Node(Node<E> prev, E element, Node<E> next) {
1.966 - this.item = element;
1.967 - this.next = next;
1.968 - this.prev = prev;
1.969 - }
1.970 - }
1.971 -
1.972 - /**
1.973 - * @since 1.6
1.974 - */
1.975 - public Iterator<E> descendingIterator() {
1.976 - return new DescendingIterator();
1.977 - }
1.978 -
1.979 - /**
1.980 - * Adapter to provide descending iterators via ListItr.previous
1.981 - */
1.982 - private class DescendingIterator implements Iterator<E> {
1.983 - private final ListItr itr = new ListItr(size());
1.984 - public boolean hasNext() {
1.985 - return itr.hasPrevious();
1.986 - }
1.987 - public E next() {
1.988 - return itr.previous();
1.989 - }
1.990 - public void remove() {
1.991 - itr.remove();
1.992 - }
1.993 - }
1.994 -
1.995 - @SuppressWarnings("unchecked")
1.996 - private LinkedList<E> superClone() {
1.997 - try {
1.998 - return (LinkedList<E>) super.clone();
1.999 - } catch (CloneNotSupportedException e) {
1.1000 - throw new InternalError();
1.1001 - }
1.1002 - }
1.1003 -
1.1004 - /**
1.1005 - * Returns a shallow copy of this {@code LinkedList}. (The elements
1.1006 - * themselves are not cloned.)
1.1007 - *
1.1008 - * @return a shallow copy of this {@code LinkedList} instance
1.1009 - */
1.1010 - public Object clone() {
1.1011 - LinkedList<E> clone = superClone();
1.1012 -
1.1013 - // Put clone into "virgin" state
1.1014 - clone.first = clone.last = null;
1.1015 - clone.size = 0;
1.1016 - clone.modCount = 0;
1.1017 -
1.1018 - // Initialize clone with our elements
1.1019 - for (Node<E> x = first; x != null; x = x.next)
1.1020 - clone.add(x.item);
1.1021 -
1.1022 - return clone;
1.1023 - }
1.1024 -
1.1025 - /**
1.1026 - * Returns an array containing all of the elements in this list
1.1027 - * in proper sequence (from first to last element).
1.1028 - *
1.1029 - * <p>The returned array will be "safe" in that no references to it are
1.1030 - * maintained by this list. (In other words, this method must allocate
1.1031 - * a new array). The caller is thus free to modify the returned array.
1.1032 - *
1.1033 - * <p>This method acts as bridge between array-based and collection-based
1.1034 - * APIs.
1.1035 - *
1.1036 - * @return an array containing all of the elements in this list
1.1037 - * in proper sequence
1.1038 - */
1.1039 - public Object[] toArray() {
1.1040 - Object[] result = new Object[size];
1.1041 - int i = 0;
1.1042 - for (Node<E> x = first; x != null; x = x.next)
1.1043 - result[i++] = x.item;
1.1044 - return result;
1.1045 - }
1.1046 -
1.1047 - /**
1.1048 - * Returns an array containing all of the elements in this list in
1.1049 - * proper sequence (from first to last element); the runtime type of
1.1050 - * the returned array is that of the specified array. If the list fits
1.1051 - * in the specified array, it is returned therein. Otherwise, a new
1.1052 - * array is allocated with the runtime type of the specified array and
1.1053 - * the size of this list.
1.1054 - *
1.1055 - * <p>If the list fits in the specified array with room to spare (i.e.,
1.1056 - * the array has more elements than the list), the element in the array
1.1057 - * immediately following the end of the list is set to {@code null}.
1.1058 - * (This is useful in determining the length of the list <i>only</i> if
1.1059 - * the caller knows that the list does not contain any null elements.)
1.1060 - *
1.1061 - * <p>Like the {@link #toArray()} method, this method acts as bridge between
1.1062 - * array-based and collection-based APIs. Further, this method allows
1.1063 - * precise control over the runtime type of the output array, and may,
1.1064 - * under certain circumstances, be used to save allocation costs.
1.1065 - *
1.1066 - * <p>Suppose {@code x} is a list known to contain only strings.
1.1067 - * The following code can be used to dump the list into a newly
1.1068 - * allocated array of {@code String}:
1.1069 - *
1.1070 - * <pre>
1.1071 - * String[] y = x.toArray(new String[0]);</pre>
1.1072 - *
1.1073 - * Note that {@code toArray(new Object[0])} is identical in function to
1.1074 - * {@code toArray()}.
1.1075 - *
1.1076 - * @param a the array into which the elements of the list are to
1.1077 - * be stored, if it is big enough; otherwise, a new array of the
1.1078 - * same runtime type is allocated for this purpose.
1.1079 - * @return an array containing the elements of the list
1.1080 - * @throws ArrayStoreException if the runtime type of the specified array
1.1081 - * is not a supertype of the runtime type of every element in
1.1082 - * this list
1.1083 - * @throws NullPointerException if the specified array is null
1.1084 - */
1.1085 - @SuppressWarnings("unchecked")
1.1086 - public <T> T[] toArray(T[] a) {
1.1087 - if (a.length < size)
1.1088 - a = (T[])java.lang.reflect.Array.newInstance(
1.1089 - a.getClass().getComponentType(), size);
1.1090 - int i = 0;
1.1091 - Object[] result = a;
1.1092 - for (Node<E> x = first; x != null; x = x.next)
1.1093 - result[i++] = x.item;
1.1094 -
1.1095 - if (a.length > size)
1.1096 - a[size] = null;
1.1097 -
1.1098 - return a;
1.1099 - }
1.1100 -
1.1101 - private static final long serialVersionUID = 876323262645176354L;
1.1102 -
1.1103 -}