8302513: remove sun.awt.util.IdentityLinkedList
Reviewed-by: serb, prr, aivanov
This commit is contained in:
parent
bf16b5b988
commit
94de0a73de
src/java.desktop/share/classes
@ -48,7 +48,6 @@ import sun.awt.AWTPermissions;
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import sun.awt.AppContext;
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import sun.awt.SunToolkit;
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import sun.awt.util.IdentityArrayList;
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import sun.awt.util.IdentityLinkedList;
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/**
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* A Dialog is a top-level window with a title and a border
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@ -1417,7 +1416,7 @@ public class Dialog extends Window {
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k++;
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}
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java.util.List<Window> toBlock = new IdentityLinkedList<Window>();
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java.util.List<Window> toBlock = new IdentityArrayList<Window>();
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// block all windows from scope of blocking except from blockers' hierarchies
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IdentityArrayList<Window> unblockedWindows = Window.getAllUnblockedWindows();
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for (Window w : unblockedWindows) {
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@ -1,880 +0,0 @@
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/*
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* Copyright (c) 2007, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.awt.util;
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import java.util.AbstractSequentialList;
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import java.util.Collection;
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import java.util.ConcurrentModificationException;
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import java.util.Deque;
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import java.util.Iterator;
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import java.util.List;
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import java.util.ListIterator;
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import java.util.NoSuchElementException;
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/**
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* Linked list implementation of the {@code List} interface. Implements all
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* optional list operations, and permits all elements (including
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* {@code null}). In addition to implementing the {@code List} interface,
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* the {@code IdentityLinkedList} class provides uniformly named methods to
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* {@code get}, {@code remove} and {@code insert} an element at the
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* beginning and end of the list. These operations allow linked lists to be
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* used as a stack, {@linkplain java.util.Queue queue}, or {@linkplain Deque
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* double-ended queue}. <p>
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*
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* The class implements the {@code Deque} interface, providing
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* first-in-first-out queue operations for {@code add},
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* {@code poll}, along with other stack and deque operations.<p>
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*
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* All of the operations perform as could be expected for a doubly-linked
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* list. Operations that index into the list will traverse the list from
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* the beginning or the end, whichever is closer to the specified index.<p>
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*
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* <p><strong>Note that this implementation is not synchronized.</strong>
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* If multiple threads access a linked list concurrently, and at least
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* one of the threads modifies the list structurally, it <i>must</i> be
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* synchronized externally. (A structural modification is any operation
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* that adds or deletes one or more elements; merely setting the value of
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* an element is not a structural modification.) This is typically
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* accomplished by synchronizing on some object that naturally
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* encapsulates the list.
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*
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* If no such object exists, the list should be "wrapped" using the
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* {@link java.util.Collections#synchronizedList Collections.synchronizedList}
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* method. This is best done at creation time, to prevent accidental
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* unsynchronized access to the list:<pre>
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* List list = Collections.synchronizedList(new IdentityLinkedList(...));</pre>
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*
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* <p>The iterators returned by this class's {@code iterator} and
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* {@code listIterator} methods are <i>fail-fast</i>: if the list is
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* structurally modified at any time after the iterator is created, in
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* any way except through the Iterator's own {@code remove} or
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* {@code add} methods, the iterator will throw a {@link
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* ConcurrentModificationException}. Thus, in the face of concurrent
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* modification, the iterator fails quickly and cleanly, rather than
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* risking arbitrary, non-deterministic behavior at an undetermined
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* time in the future.
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*
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* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
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* as it is, generally speaking, impossible to make any hard guarantees in the
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* presence of unsynchronized concurrent modification. Fail-fast iterators
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* throw {@code ConcurrentModificationException} on a best-effort basis.
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* Therefore, it would be wrong to write a program that depended on this
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* exception for its correctness: <i>the fail-fast behavior of iterators
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* should be used only to detect bugs.</i>
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*/
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public class IdentityLinkedList<E>
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extends AbstractSequentialList<E>
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implements List<E>, Deque<E>
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{
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private transient Entry<E> header = new Entry<E>(null, null, null);
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private transient int size = 0;
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/**
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* Constructs an empty list.
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*/
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public IdentityLinkedList() {
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header.next = header.previous = header;
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}
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/**
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* Constructs a list containing the elements of the specified
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* collection, in the order they are returned by the collection's
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* iterator.
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*
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* @param c the collection whose elements are to be placed into this list
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* @throws NullPointerException if the specified collection is null
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*/
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public IdentityLinkedList(Collection<? extends E> c) {
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this();
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addAll(c);
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}
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/**
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* Returns the first element in this list.
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*
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* @return the first element in this list
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* @throws NoSuchElementException if this list is empty
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*/
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public E getFirst() {
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if (size==0)
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throw new NoSuchElementException();
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return header.next.element;
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}
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/**
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* Returns the last element in this list.
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*
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* @return the last element in this list
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* @throws NoSuchElementException if this list is empty
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*/
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public E getLast() {
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if (size==0)
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throw new NoSuchElementException();
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return header.previous.element;
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}
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/**
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* Removes and returns the first element from this list.
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*
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* @return the first element from this list
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* @throws NoSuchElementException if this list is empty
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*/
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public E removeFirst() {
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return remove(header.next);
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}
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/**
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* Removes and returns the last element from this list.
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*
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* @return the last element from this list
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* @throws NoSuchElementException if this list is empty
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*/
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public E removeLast() {
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return remove(header.previous);
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}
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/**
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* Inserts the specified element at the beginning of this list.
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*
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* @param e the element to add
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*/
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public void addFirst(E e) {
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addBefore(e, header.next);
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}
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/**
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* Appends the specified element to the end of this list.
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*
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* <p>This method is equivalent to {@link #add}.
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*
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* @param e the element to add
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*/
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public void addLast(E e) {
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addBefore(e, header);
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}
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/**
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* Returns {@code true} if this list contains the specified element.
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* More formally, returns {@code true} if and only if this list contains
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* at least one element {@code e} such that
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* {@code o == e}.
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*
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* @param o element whose presence in this list is to be tested
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* @return {@code true} if this list contains the specified element
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*/
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public boolean contains(Object o) {
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return indexOf(o) != -1;
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}
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/**
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* Returns the number of elements in this list.
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*
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* @return the number of elements in this list
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*/
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public int size() {
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return size;
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}
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/**
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* Appends the specified element to the end of this list.
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*
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* <p>This method is equivalent to {@link #addLast}.
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*
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* @param e element to be appended to this list
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* @return {@code true} (as specified by {@link Collection#add})
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*/
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public boolean add(E e) {
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addBefore(e, header);
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return true;
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}
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/**
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* Removes the first occurrence of the specified element from this list,
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* if it is present. If this list does not contain the element, it is
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* unchanged. More formally, removes the element with the lowest index
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* {@code i} such that {@code get(i) == o}
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* (if such an element exists). Returns {@code true} if this list
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* contained the specified element (or equivalently, if this list
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* changed as a result of the call).
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*
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* @param o element to be removed from this list, if present
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* @return {@code true} if this list contained the specified element
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*/
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public boolean remove(Object o) {
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for (Entry<E> e = header.next; e != header; e = e.next) {
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if (o == e.element) {
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remove(e);
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return true;
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}
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}
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return false;
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}
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/**
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* Appends all of the elements in the specified collection to the end of
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* this list, in the order that they are returned by the specified
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* collection's iterator. The behavior of this operation is undefined if
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* the specified collection is modified while the operation is in
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* progress. (Note that this will occur if the specified collection is
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* this list, and it's nonempty.)
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*
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* @param c collection containing elements to be added to this list
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* @return {@code true} if this list changed as a result of the call
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* @throws NullPointerException if the specified collection is null
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*/
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public boolean addAll(Collection<? extends E> c) {
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return addAll(size, c);
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}
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/**
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* Inserts all of the elements in the specified collection into this
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* list, starting at the specified position. Shifts the element
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* currently at that position (if any) and any subsequent elements to
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* the right (increases their indices). The new elements will appear
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* in the list in the order that they are returned by the
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* specified collection's iterator.
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*
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* @param index index at which to insert the first element
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* from the specified collection
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* @param c collection containing elements to be added to this list
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* @return {@code true} if this list changed as a result of the call
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* @throws IndexOutOfBoundsException {@inheritDoc}
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* @throws NullPointerException if the specified collection is null
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*/
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public boolean addAll(int index, Collection<? extends E> c) {
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if (index < 0 || index > size)
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throw new IndexOutOfBoundsException("Index: "+index+
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", Size: "+size);
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Object[] a = c.toArray();
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int numNew = a.length;
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if (numNew==0)
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return false;
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modCount++;
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Entry<E> successor = (index==size ? header : entry(index));
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Entry<E> predecessor = successor.previous;
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for (int i=0; i<numNew; i++) {
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@SuppressWarnings("unchecked")
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E tmp = (E) a[i];
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Entry<E> e = new Entry<E>(tmp, successor, predecessor);
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predecessor.next = e;
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predecessor = e;
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}
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successor.previous = predecessor;
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size += numNew;
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return true;
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}
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/**
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* Removes all of the elements from this list.
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*/
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public void clear() {
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Entry<E> e = header.next;
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while (e != header) {
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Entry<E> next = e.next;
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e.next = e.previous = null;
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e.element = null;
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e = next;
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}
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header.next = header.previous = header;
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size = 0;
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modCount++;
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}
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// Positional Access Operations
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/**
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* Returns the element at the specified position in this list.
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*
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* @param index index of the element to return
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* @return the element at the specified position in this list
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* @throws IndexOutOfBoundsException {@inheritDoc}
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*/
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public E get(int index) {
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return entry(index).element;
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}
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/**
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* Replaces the element at the specified position in this list with the
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* specified element.
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*
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* @param index index of the element to replace
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* @param element element to be stored at the specified position
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* @return the element previously at the specified position
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* @throws IndexOutOfBoundsException {@inheritDoc}
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*/
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public E set(int index, E element) {
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Entry<E> e = entry(index);
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E oldVal = e.element;
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e.element = element;
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return oldVal;
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}
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/**
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* Inserts the specified element at the specified position in this list.
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* Shifts the element currently at that position (if any) and any
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* subsequent elements to the right (adds one to their indices).
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*
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* @param index index at which the specified element is to be inserted
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* @param element element to be inserted
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* @throws IndexOutOfBoundsException {@inheritDoc}
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*/
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public void add(int index, E element) {
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addBefore(element, (index==size ? header : entry(index)));
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}
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/**
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* Removes the element at the specified position in this list. Shifts any
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* subsequent elements to the left (subtracts one from their indices).
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* Returns the element that was removed from the list.
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*
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* @param index the index of the element to be removed
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* @return the element previously at the specified position
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* @throws IndexOutOfBoundsException {@inheritDoc}
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*/
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public E remove(int index) {
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return remove(entry(index));
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}
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/**
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* Returns the indexed entry.
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*/
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private Entry<E> entry(int index) {
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if (index < 0 || index >= size)
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throw new IndexOutOfBoundsException("Index: "+index+
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", Size: "+size);
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Entry<E> e = header;
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if (index < (size >> 1)) {
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for (int i = 0; i <= index; i++)
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e = e.next;
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} else {
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for (int i = size; i > index; i--)
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e = e.previous;
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}
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return e;
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}
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// Search Operations
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/**
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* Returns the index of the first occurrence of the specified element
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* in this list, or -1 if this list does not contain the element.
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* More formally, returns the lowest index {@code i} such that
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* {@code get(i) == o},
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* or -1 if there is no such index.
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*
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* @param o element to search for
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* @return the index of the first occurrence of the specified element in
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* this list, or -1 if this list does not contain the element
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*/
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public int indexOf(Object o) {
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int index = 0;
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for (Entry<E> e = header.next; e != header; e = e.next) {
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if (o == e.element) {
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return index;
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}
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index++;
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}
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return -1;
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}
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/**
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* Returns the index of the last occurrence of the specified element
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* in this list, or -1 if this list does not contain the element.
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* More formally, returns the highest index {@code i} such that
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* {@code get(i) == o},
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* or -1 if there is no such index.
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*
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* @param o element to search for
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* @return the index of the last occurrence of the specified element in
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* this list, or -1 if this list does not contain the element
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*/
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public int lastIndexOf(Object o) {
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int index = size;
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for (Entry<E> e = header.previous; e != header; e = e.previous) {
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index--;
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if (o == e.element) {
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return index;
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}
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}
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return -1;
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}
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// Queue operations.
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/**
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* Retrieves, but does not remove, the head (first element) of this list.
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* @return the head of this list, or {@code null} if this list is empty
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* @since 1.5
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*/
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public E peek() {
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if (size==0)
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return null;
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return getFirst();
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}
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/**
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* Retrieves, but does not remove, the head (first element) of this list.
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* @return the head of this list
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* @throws NoSuchElementException if this list is empty
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* @since 1.5
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*/
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public E element() {
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return getFirst();
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}
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/**
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* Retrieves and removes the head (first element) of this list
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* @return the head of this list, or {@code null} if this list is empty
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* @since 1.5
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*/
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public E poll() {
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if (size==0)
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return null;
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return removeFirst();
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}
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/**
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* Retrieves and removes the head (first element) of this list.
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*
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* @return the head of this list
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* @throws NoSuchElementException if this list is empty
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* @since 1.5
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*/
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public E remove() {
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return removeFirst();
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}
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/**
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* Adds the specified element as the tail (last element) of this list.
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*
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* @param e the element to add
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* @return {@code true} (as specified by {@link java.util.Queue#offer})
|
||||
* @since 1.5
|
||||
*/
|
||||
public boolean offer(E e) {
|
||||
return add(e);
|
||||
}
|
||||
|
||||
// Deque operations
|
||||
/**
|
||||
* Inserts the specified element at the front of this list.
|
||||
*
|
||||
* @param e the element to insert
|
||||
* @return {@code true} (as specified by {@link Deque#offerFirst})
|
||||
* @since 1.6
|
||||
*/
|
||||
public boolean offerFirst(E e) {
|
||||
addFirst(e);
|
||||
return true;
|
||||
}
|
||||
|
||||
/**
|
||||
* Inserts the specified element at the end of this list.
|
||||
*
|
||||
* @param e the element to insert
|
||||
* @return {@code true} (as specified by {@link Deque#offerLast})
|
||||
* @since 1.6
|
||||
*/
|
||||
public boolean offerLast(E e) {
|
||||
addLast(e);
|
||||
return true;
|
||||
}
|
||||
|
||||
/**
|
||||
* Retrieves, but does not remove, the first element of this list,
|
||||
* or returns {@code null} if this list is empty.
|
||||
*
|
||||
* @return the first element of this list, or {@code null}
|
||||
* if this list is empty
|
||||
* @since 1.6
|
||||
*/
|
||||
public E peekFirst() {
|
||||
if (size==0)
|
||||
return null;
|
||||
return getFirst();
|
||||
}
|
||||
|
||||
/**
|
||||
* Retrieves, but does not remove, the last element of this list,
|
||||
* or returns {@code null} if this list is empty.
|
||||
*
|
||||
* @return the last element of this list, or {@code null}
|
||||
* if this list is empty
|
||||
* @since 1.6
|
||||
*/
|
||||
public E peekLast() {
|
||||
if (size==0)
|
||||
return null;
|
||||
return getLast();
|
||||
}
|
||||
|
||||
/**
|
||||
* Retrieves and removes the first element of this list,
|
||||
* or returns {@code null} if this list is empty.
|
||||
*
|
||||
* @return the first element of this list, or {@code null} if
|
||||
* this list is empty
|
||||
* @since 1.6
|
||||
*/
|
||||
public E pollFirst() {
|
||||
if (size==0)
|
||||
return null;
|
||||
return removeFirst();
|
||||
}
|
||||
|
||||
/**
|
||||
* Retrieves and removes the last element of this list,
|
||||
* or returns {@code null} if this list is empty.
|
||||
*
|
||||
* @return the last element of this list, or {@code null} if
|
||||
* this list is empty
|
||||
* @since 1.6
|
||||
*/
|
||||
public E pollLast() {
|
||||
if (size==0)
|
||||
return null;
|
||||
return removeLast();
|
||||
}
|
||||
|
||||
/**
|
||||
* Pushes an element onto the stack represented by this list. In other
|
||||
* words, inserts the element at the front of this list.
|
||||
*
|
||||
* <p>This method is equivalent to {@link #addFirst}.
|
||||
*
|
||||
* @param e the element to push
|
||||
* @since 1.6
|
||||
*/
|
||||
public void push(E e) {
|
||||
addFirst(e);
|
||||
}
|
||||
|
||||
/**
|
||||
* Pops an element from the stack represented by this list. In other
|
||||
* words, removes and returns the first element of this list.
|
||||
*
|
||||
* <p>This method is equivalent to {@link #removeFirst()}.
|
||||
*
|
||||
* @return the element at the front of this list (which is the top
|
||||
* of the stack represented by this list)
|
||||
* @throws NoSuchElementException if this list is empty
|
||||
* @since 1.6
|
||||
*/
|
||||
public E pop() {
|
||||
return removeFirst();
|
||||
}
|
||||
|
||||
/**
|
||||
* Removes the first occurrence of the specified element in this
|
||||
* list (when traversing the list from head to tail). If the list
|
||||
* does not contain the element, it is unchanged.
|
||||
*
|
||||
* @param o element to be removed from this list, if present
|
||||
* @return {@code true} if the list contained the specified element
|
||||
* @since 1.6
|
||||
*/
|
||||
public boolean removeFirstOccurrence(Object o) {
|
||||
return remove(o);
|
||||
}
|
||||
|
||||
/**
|
||||
* Removes the last occurrence of the specified element in this
|
||||
* list (when traversing the list from head to tail). If the list
|
||||
* does not contain the element, it is unchanged.
|
||||
*
|
||||
* @param o element to be removed from this list, if present
|
||||
* @return {@code true} if the list contained the specified element
|
||||
* @since 1.6
|
||||
*/
|
||||
public boolean removeLastOccurrence(Object o) {
|
||||
for (Entry<E> e = header.previous; e != header; e = e.previous) {
|
||||
if (o == e.element) {
|
||||
remove(e);
|
||||
return true;
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns a list-iterator of the elements in this list (in proper
|
||||
* sequence), starting at the specified position in the list.
|
||||
* Obeys the general contract of {@code List.listIterator(int)}.<p>
|
||||
*
|
||||
* The list-iterator is <i>fail-fast</i>: if the list is structurally
|
||||
* modified at any time after the Iterator is created, in any way except
|
||||
* through the list-iterator's own {@code remove} or {@code add}
|
||||
* methods, the list-iterator will throw a
|
||||
* {@code ConcurrentModificationException}. Thus, in the face of
|
||||
* concurrent modification, the iterator fails quickly and cleanly, rather
|
||||
* than risking arbitrary, non-deterministic behavior at an undetermined
|
||||
* time in the future.
|
||||
*
|
||||
* @param index index of the first element to be returned from the
|
||||
* list-iterator (by a call to {@code next})
|
||||
* @return a ListIterator of the elements in this list (in proper
|
||||
* sequence), starting at the specified position in the list
|
||||
* @throws IndexOutOfBoundsException {@inheritDoc}
|
||||
* @see List#listIterator(int)
|
||||
*/
|
||||
public ListIterator<E> listIterator(int index) {
|
||||
return new ListItr(index);
|
||||
}
|
||||
|
||||
private class ListItr implements ListIterator<E> {
|
||||
private Entry<E> lastReturned = header;
|
||||
private Entry<E> next;
|
||||
private int nextIndex;
|
||||
private int expectedModCount = modCount;
|
||||
|
||||
ListItr(int index) {
|
||||
if (index < 0 || index > size)
|
||||
throw new IndexOutOfBoundsException("Index: "+index+
|
||||
", Size: "+size);
|
||||
if (index < (size >> 1)) {
|
||||
next = header.next;
|
||||
for (nextIndex=0; nextIndex<index; nextIndex++)
|
||||
next = next.next;
|
||||
} else {
|
||||
next = header;
|
||||
for (nextIndex=size; nextIndex>index; nextIndex--)
|
||||
next = next.previous;
|
||||
}
|
||||
}
|
||||
|
||||
public boolean hasNext() {
|
||||
return nextIndex != size;
|
||||
}
|
||||
|
||||
public E next() {
|
||||
checkForComodification();
|
||||
if (nextIndex == size)
|
||||
throw new NoSuchElementException();
|
||||
|
||||
lastReturned = next;
|
||||
next = next.next;
|
||||
nextIndex++;
|
||||
return lastReturned.element;
|
||||
}
|
||||
|
||||
public boolean hasPrevious() {
|
||||
return nextIndex != 0;
|
||||
}
|
||||
|
||||
public E previous() {
|
||||
if (nextIndex == 0)
|
||||
throw new NoSuchElementException();
|
||||
|
||||
lastReturned = next = next.previous;
|
||||
nextIndex--;
|
||||
checkForComodification();
|
||||
return lastReturned.element;
|
||||
}
|
||||
|
||||
public int nextIndex() {
|
||||
return nextIndex;
|
||||
}
|
||||
|
||||
public int previousIndex() {
|
||||
return nextIndex-1;
|
||||
}
|
||||
|
||||
public void remove() {
|
||||
checkForComodification();
|
||||
Entry<E> lastNext = lastReturned.next;
|
||||
try {
|
||||
IdentityLinkedList.this.remove(lastReturned);
|
||||
} catch (NoSuchElementException e) {
|
||||
throw new IllegalStateException();
|
||||
}
|
||||
if (next==lastReturned)
|
||||
next = lastNext;
|
||||
else
|
||||
nextIndex--;
|
||||
lastReturned = header;
|
||||
expectedModCount++;
|
||||
}
|
||||
|
||||
public void set(E e) {
|
||||
if (lastReturned == header)
|
||||
throw new IllegalStateException();
|
||||
checkForComodification();
|
||||
lastReturned.element = e;
|
||||
}
|
||||
|
||||
public void add(E e) {
|
||||
checkForComodification();
|
||||
lastReturned = header;
|
||||
addBefore(e, next);
|
||||
nextIndex++;
|
||||
expectedModCount++;
|
||||
}
|
||||
|
||||
final void checkForComodification() {
|
||||
if (modCount != expectedModCount)
|
||||
throw new ConcurrentModificationException();
|
||||
}
|
||||
}
|
||||
|
||||
private static class Entry<E> {
|
||||
E element;
|
||||
Entry<E> next;
|
||||
Entry<E> previous;
|
||||
|
||||
Entry(E element, Entry<E> next, Entry<E> previous) {
|
||||
this.element = element;
|
||||
this.next = next;
|
||||
this.previous = previous;
|
||||
}
|
||||
}
|
||||
|
||||
private Entry<E> addBefore(E e, Entry<E> entry) {
|
||||
Entry<E> newEntry = new Entry<E>(e, entry, entry.previous);
|
||||
newEntry.previous.next = newEntry;
|
||||
newEntry.next.previous = newEntry;
|
||||
size++;
|
||||
modCount++;
|
||||
return newEntry;
|
||||
}
|
||||
|
||||
private E remove(Entry<E> e) {
|
||||
if (e == header)
|
||||
throw new NoSuchElementException();
|
||||
|
||||
E result = e.element;
|
||||
e.previous.next = e.next;
|
||||
e.next.previous = e.previous;
|
||||
e.next = e.previous = null;
|
||||
e.element = null;
|
||||
size--;
|
||||
modCount++;
|
||||
return result;
|
||||
}
|
||||
|
||||
/**
|
||||
* @since 1.6
|
||||
*/
|
||||
public Iterator<E> descendingIterator() {
|
||||
return new DescendingIterator();
|
||||
}
|
||||
|
||||
/** Adapter to provide descending iterators via ListItr.previous */
|
||||
private class DescendingIterator implements Iterator<E> {
|
||||
final ListItr itr = new ListItr(size());
|
||||
public boolean hasNext() {
|
||||
return itr.hasPrevious();
|
||||
}
|
||||
public E next() {
|
||||
return itr.previous();
|
||||
}
|
||||
public void remove() {
|
||||
itr.remove();
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns an array containing all of the elements in this list
|
||||
* in proper sequence (from first to last element).
|
||||
*
|
||||
* <p>The returned array will be "safe" in that no references to it are
|
||||
* maintained by this list. (In other words, this method must allocate
|
||||
* a new array). The caller is thus free to modify the returned array.
|
||||
*
|
||||
* <p>This method acts as bridge between array-based and collection-based
|
||||
* APIs.
|
||||
*
|
||||
* @return an array containing all of the elements in this list
|
||||
* in proper sequence
|
||||
*/
|
||||
public Object[] toArray() {
|
||||
Object[] result = new Object[size];
|
||||
int i = 0;
|
||||
for (Entry<E> e = header.next; e != header; e = e.next)
|
||||
result[i++] = e.element;
|
||||
return result;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns an array containing all of the elements in this list in
|
||||
* proper sequence (from first to last element); the runtime type of
|
||||
* the returned array is that of the specified array. If the list fits
|
||||
* in the specified array, it is returned therein. Otherwise, a new
|
||||
* array is allocated with the runtime type of the specified array and
|
||||
* the size of this list.
|
||||
*
|
||||
* <p>If the list fits in the specified array with room to spare (i.e.,
|
||||
* the array has more elements than the list), the element in the array
|
||||
* immediately following the end of the list is set to {@code null}.
|
||||
* (This is useful in determining the length of the list <i>only</i> if
|
||||
* the caller knows that the list does not contain any null elements.)
|
||||
*
|
||||
* <p>Like the {@link #toArray()} method, this method acts as bridge between
|
||||
* array-based and collection-based APIs. Further, this method allows
|
||||
* precise control over the runtime type of the output array, and may,
|
||||
* under certain circumstances, be used to save allocation costs.
|
||||
*
|
||||
* <p>Suppose {@code x} is a list known to contain only strings.
|
||||
* The following code can be used to dump the list into a newly
|
||||
* allocated array of {@code String}:
|
||||
*
|
||||
* <pre>
|
||||
* String[] y = x.toArray(new String[0]);</pre>
|
||||
*
|
||||
* Note that {@code toArray(new Object[0])} is identical in function to
|
||||
* {@code toArray()}.
|
||||
*
|
||||
* @param a the array into which the elements of the list are to
|
||||
* be stored, if it is big enough; otherwise, a new array of the
|
||||
* same runtime type is allocated for this purpose.
|
||||
* @return an array containing the elements of the list
|
||||
* @throws ArrayStoreException if the runtime type of the specified array
|
||||
* is not a supertype of the runtime type of every element in
|
||||
* this list
|
||||
* @throws NullPointerException if the specified array is null
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public <T> T[] toArray(T[] a) {
|
||||
if (a.length < size)
|
||||
a = (T[])java.lang.reflect.Array.newInstance(
|
||||
a.getClass().getComponentType(), size);
|
||||
int i = 0;
|
||||
Object[] result = a;
|
||||
for (Entry<E> e = header.next; e != header; e = e.next)
|
||||
result[i++] = e.element;
|
||||
|
||||
if (a.length > size)
|
||||
a[size] = null;
|
||||
|
||||
return a;
|
||||
}
|
||||
}
|
Loading…
x
Reference in New Issue
Block a user