--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.base/share/classes/java/util/LinkedHashSet.java Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,195 @@
+/*
+ * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.util;
+
+/**
+ * <p>Hash table and linked list implementation of the <tt>Set</tt> interface,
+ * with predictable iteration order. This implementation differs from
+ * <tt>HashSet</tt> in that it maintains a doubly-linked list running through
+ * all of its entries. This linked list defines the iteration ordering,
+ * which is the order in which elements were inserted into the set
+ * (<i>insertion-order</i>). Note that insertion order is <i>not</i> affected
+ * if an element is <i>re-inserted</i> into the set. (An element <tt>e</tt>
+ * is reinserted into a set <tt>s</tt> if <tt>s.add(e)</tt> is invoked when
+ * <tt>s.contains(e)</tt> would return <tt>true</tt> immediately prior to
+ * the invocation.)
+ *
+ * <p>This implementation spares its clients from the unspecified, generally
+ * chaotic ordering provided by {@link HashSet}, without incurring the
+ * increased cost associated with {@link TreeSet}. It can be used to
+ * produce a copy of a set that has the same order as the original, regardless
+ * of the original set's implementation:
+ * <pre>
+ * void foo(Set s) {
+ * Set copy = new LinkedHashSet(s);
+ * ...
+ * }
+ * </pre>
+ * This technique is particularly useful if a module takes a set on input,
+ * copies it, and later returns results whose order is determined by that of
+ * the copy. (Clients generally appreciate having things returned in the same
+ * order they were presented.)
+ *
+ * <p>This class provides all of the optional <tt>Set</tt> operations, and
+ * permits null elements. Like <tt>HashSet</tt>, it provides constant-time
+ * performance for the basic operations (<tt>add</tt>, <tt>contains</tt> and
+ * <tt>remove</tt>), assuming the hash function disperses elements
+ * properly among the buckets. Performance is likely to be just slightly
+ * below that of <tt>HashSet</tt>, due to the added expense of maintaining the
+ * linked list, with one exception: Iteration over a <tt>LinkedHashSet</tt>
+ * requires time proportional to the <i>size</i> of the set, regardless of
+ * its capacity. Iteration over a <tt>HashSet</tt> is likely to be more
+ * expensive, requiring time proportional to its <i>capacity</i>.
+ *
+ * <p>A linked hash set has two parameters that affect its performance:
+ * <i>initial capacity</i> and <i>load factor</i>. They are defined precisely
+ * as for <tt>HashSet</tt>. Note, however, that the penalty for choosing an
+ * excessively high value for initial capacity is less severe for this class
+ * than for <tt>HashSet</tt>, as iteration times for this class are unaffected
+ * by capacity.
+ *
+ * <p><strong>Note that this implementation is not synchronized.</strong>
+ * If multiple threads access a linked hash set concurrently, and at least
+ * one of the threads modifies the set, it <em>must</em> be synchronized
+ * externally. This is typically accomplished by synchronizing on some
+ * object that naturally encapsulates the set.
+ *
+ * If no such object exists, the set should be "wrapped" using the
+ * {@link Collections#synchronizedSet Collections.synchronizedSet}
+ * method. This is best done at creation time, to prevent accidental
+ * unsynchronized access to the set: <pre>
+ * Set s = Collections.synchronizedSet(new LinkedHashSet(...));</pre>
+ *
+ * <p>The iterators returned by this class's <tt>iterator</tt> method are
+ * <em>fail-fast</em>: if the set is modified at any time after the iterator
+ * is created, in any way except through the iterator's own <tt>remove</tt>
+ * method, the iterator will throw a {@link 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.
+ *
+ * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
+ * as it is, generally speaking, impossible to make any hard guarantees in the
+ * presence of unsynchronized concurrent modification. Fail-fast iterators
+ * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
+ * Therefore, it would be wrong to write a program that depended on this
+ * exception for its correctness: <i>the fail-fast behavior of iterators
+ * should be used only to detect bugs.</i>
+ *
+ * <p>This class is a member of the
+ * <a href="{@docRoot}/../technotes/guides/collections/index.html">
+ * Java Collections Framework</a>.
+ *
+ * @param <E> the type of elements maintained by this set
+ *
+ * @author Josh Bloch
+ * @see Object#hashCode()
+ * @see Collection
+ * @see Set
+ * @see HashSet
+ * @see TreeSet
+ * @see Hashtable
+ * @since 1.4
+ */
+
+public class LinkedHashSet<E>
+ extends HashSet<E>
+ implements Set<E>, Cloneable, java.io.Serializable {
+
+ private static final long serialVersionUID = -2851667679971038690L;
+
+ /**
+ * Constructs a new, empty linked hash set with the specified initial
+ * capacity and load factor.
+ *
+ * @param initialCapacity the initial capacity of the linked hash set
+ * @param loadFactor the load factor of the linked hash set
+ * @throws IllegalArgumentException if the initial capacity is less
+ * than zero, or if the load factor is nonpositive
+ */
+ public LinkedHashSet(int initialCapacity, float loadFactor) {
+ super(initialCapacity, loadFactor, true);
+ }
+
+ /**
+ * Constructs a new, empty linked hash set with the specified initial
+ * capacity and the default load factor (0.75).
+ *
+ * @param initialCapacity the initial capacity of the LinkedHashSet
+ * @throws IllegalArgumentException if the initial capacity is less
+ * than zero
+ */
+ public LinkedHashSet(int initialCapacity) {
+ super(initialCapacity, .75f, true);
+ }
+
+ /**
+ * Constructs a new, empty linked hash set with the default initial
+ * capacity (16) and load factor (0.75).
+ */
+ public LinkedHashSet() {
+ super(16, .75f, true);
+ }
+
+ /**
+ * Constructs a new linked hash set with the same elements as the
+ * specified collection. The linked hash set is created with an initial
+ * capacity sufficient to hold the elements in the specified collection
+ * and the default load factor (0.75).
+ *
+ * @param c the collection whose elements are to be placed into
+ * this set
+ * @throws NullPointerException if the specified collection is null
+ */
+ public LinkedHashSet(Collection<? extends E> c) {
+ super(Math.max(2*c.size(), 11), .75f, true);
+ addAll(c);
+ }
+
+ /**
+ * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
+ * and <em>fail-fast</em> {@code Spliterator} over the elements in this set.
+ *
+ * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
+ * {@link Spliterator#DISTINCT}, and {@code ORDERED}. Implementations
+ * should document the reporting of additional characteristic values.
+ *
+ * @implNote
+ * The implementation creates a
+ * <em><a href="Spliterator.html#binding">late-binding</a></em> spliterator
+ * from the set's {@code Iterator}. The spliterator inherits the
+ * <em>fail-fast</em> properties of the set's iterator.
+ * The created {@code Spliterator} additionally reports
+ * {@link Spliterator#SUBSIZED}.
+ *
+ * @return a {@code Spliterator} over the elements in this set
+ * @since 1.8
+ */
+ @Override
+ public Spliterator<E> spliterator() {
+ return Spliterators.spliterator(this, Spliterator.DISTINCT | Spliterator.ORDERED);
+ }
+}