author | bchristi |
Tue, 04 Jun 2013 10:04:28 +0100 | |
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parent 16867 | 76499721c6c1 |
child 18166 | a24e00a7c5ae |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1994, 2013, 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 java.util; |
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import java.io.*; |
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import java.util.function.BiConsumer; |
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import java.util.function.Function; |
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import java.util.function.BiFunction; |
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/** |
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* This class implements a hash table, which maps keys to values. Any |
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* non-<code>null</code> object can be used as a key or as a value. <p> |
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* |
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* To successfully store and retrieve objects from a hashtable, the |
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* objects used as keys must implement the <code>hashCode</code> |
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* method and the <code>equals</code> method. <p> |
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* |
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* An instance of <code>Hashtable</code> has two parameters that affect its |
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* performance: <i>initial capacity</i> and <i>load factor</i>. The |
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* <i>capacity</i> is the number of <i>buckets</i> in the hash table, and the |
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* <i>initial capacity</i> is simply the capacity at the time the hash table |
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* is created. Note that the hash table is <i>open</i>: in the case of a "hash |
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* collision", a single bucket stores multiple entries, which must be searched |
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* sequentially. The <i>load factor</i> is a measure of how full the hash |
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* table is allowed to get before its capacity is automatically increased. |
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* The initial capacity and load factor parameters are merely hints to |
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* the implementation. The exact details as to when and whether the rehash |
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* method is invoked are implementation-dependent.<p> |
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* |
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* Generally, the default load factor (.75) offers a good tradeoff between |
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* time and space costs. Higher values decrease the space overhead but |
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* increase the time cost to look up an entry (which is reflected in most |
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* <tt>Hashtable</tt> operations, including <tt>get</tt> and <tt>put</tt>).<p> |
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* |
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* The initial capacity controls a tradeoff between wasted space and the |
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* need for <code>rehash</code> operations, which are time-consuming. |
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* No <code>rehash</code> operations will <i>ever</i> occur if the initial |
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* capacity is greater than the maximum number of entries the |
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* <tt>Hashtable</tt> will contain divided by its load factor. However, |
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* setting the initial capacity too high can waste space.<p> |
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* |
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* If many entries are to be made into a <code>Hashtable</code>, |
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* creating it with a sufficiently large capacity may allow the |
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* entries to be inserted more efficiently than letting it perform |
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* automatic rehashing as needed to grow the table. <p> |
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* |
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* This example creates a hashtable of numbers. It uses the names of |
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* the numbers as keys: |
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* <pre> {@code |
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* Hashtable<String, Integer> numbers |
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* = new Hashtable<String, Integer>(); |
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* numbers.put("one", 1); |
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* numbers.put("two", 2); |
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* numbers.put("three", 3);}</pre> |
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* |
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* <p>To retrieve a number, use the following code: |
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* <pre> {@code |
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* Integer n = numbers.get("two"); |
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* if (n != null) { |
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* System.out.println("two = " + n); |
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* }}</pre> |
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* |
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* <p>The iterators returned by the <tt>iterator</tt> method of the collections |
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* returned by all of this class's "collection view methods" are |
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* <em>fail-fast</em>: if the Hashtable is structurally modified at any time |
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* after the iterator is created, in any way except through the iterator's own |
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* <tt>remove</tt> method, 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 risking |
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* arbitrary, non-deterministic behavior at an undetermined time in the future. |
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* The Enumerations returned by Hashtable's keys and elements methods are |
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* <em>not</em> fail-fast. |
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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 <tt>ConcurrentModificationException</tt> 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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* <p>As of the Java 2 platform v1.2, this class was retrofitted to |
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* implement the {@link Map} interface, making it a member of the |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* |
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* Java Collections Framework</a>. Unlike the new collection |
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* implementations, {@code Hashtable} is synchronized. If a |
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* thread-safe implementation is not needed, it is recommended to use |
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* {@link HashMap} in place of {@code Hashtable}. If a thread-safe |
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* highly-concurrent implementation is desired, then it is recommended |
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* to use {@link java.util.concurrent.ConcurrentHashMap} in place of |
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* {@code Hashtable}. |
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* |
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* @author Arthur van Hoff |
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* @author Josh Bloch |
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* @author Neal Gafter |
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* @see Object#equals(java.lang.Object) |
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* @see Object#hashCode() |
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* @see Hashtable#rehash() |
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* @see Collection |
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* @see Map |
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* @see HashMap |
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* @see TreeMap |
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* @since JDK1.0 |
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*/ |
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public class Hashtable<K,V> |
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extends Dictionary<K,V> |
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implements Map<K,V>, Cloneable, java.io.Serializable { |
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/** |
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* The hash table data. |
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*/ |
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private transient Entry<?,?>[] table; |
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/** |
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* The total number of entries in the hash table. |
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*/ |
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private transient int count; |
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/** |
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* The table is rehashed when its size exceeds this threshold. (The |
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* value of this field is (int)(capacity * loadFactor).) |
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* |
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* @serial |
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*/ |
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private int threshold; |
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/** |
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* The load factor for the hashtable. |
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* |
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* @serial |
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*/ |
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private float loadFactor; |
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/** |
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* The number of times this Hashtable has been structurally modified |
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* Structural modifications are those that change the number of entries in |
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* the Hashtable or otherwise modify its internal structure (e.g., |
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* rehash). This field is used to make iterators on Collection-views of |
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* the Hashtable fail-fast. (See ConcurrentModificationException). |
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*/ |
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private transient int modCount = 0; |
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/** use serialVersionUID from JDK 1.0.2 for interoperability */ |
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private static final long serialVersionUID = 1421746759512286392L; |
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private static class Holder { |
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// Unsafe mechanics |
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/** |
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* |
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*/ |
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static final sun.misc.Unsafe UNSAFE; |
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/** |
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* Offset of "final" hashSeed field we must set in |
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* readObject() method. |
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*/ |
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static final long HASHSEED_OFFSET; |
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static final boolean USE_HASHSEED; |
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static { |
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String hashSeedProp = java.security.AccessController.doPrivileged( |
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new sun.security.action.GetPropertyAction( |
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"jdk.map.useRandomSeed")); |
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boolean localBool = (null != hashSeedProp) |
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? Boolean.parseBoolean(hashSeedProp) : false; |
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USE_HASHSEED = localBool; |
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if (USE_HASHSEED) { |
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try { |
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UNSAFE = sun.misc.Unsafe.getUnsafe(); |
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HASHSEED_OFFSET = UNSAFE.objectFieldOffset( |
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Hashtable.class.getDeclaredField("hashSeed")); |
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} catch (NoSuchFieldException | SecurityException e) { |
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throw new InternalError("Failed to record hashSeed offset", e); |
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} |
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} else { |
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UNSAFE = null; |
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HASHSEED_OFFSET = 0; |
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} |
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} |
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} |
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/** |
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* A randomizing value associated with this instance that is applied to |
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* hash code of keys to make hash collisions harder to find. |
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* |
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* Non-final so it can be set lazily, but be sure not to set more than once. |
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*/ |
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transient final int hashSeed; |
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|
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/** |
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* Return an initial value for the hashSeed, or 0 if the random seed is not |
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* enabled. |
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*/ |
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final int initHashSeed() { |
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if (sun.misc.VM.isBooted() && Holder.USE_HASHSEED) { |
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return sun.misc.Hashing.randomHashSeed(this); |
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} |
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return 0; |
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} |
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private int hash(Object k) { |
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return hashSeed ^ k.hashCode(); |
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} |
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/** |
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* Constructs a new, empty hashtable with the specified initial |
|
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* capacity and the specified load factor. |
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* |
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* @param initialCapacity the initial capacity of the hashtable. |
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* @param loadFactor the load factor of the hashtable. |
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* @exception IllegalArgumentException if the initial capacity is less |
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* than zero, or if the load factor is nonpositive. |
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*/ |
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public Hashtable(int initialCapacity, float loadFactor) { |
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if (initialCapacity < 0) |
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throw new IllegalArgumentException("Illegal Capacity: "+ |
|
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initialCapacity); |
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if (loadFactor <= 0 || Float.isNaN(loadFactor)) |
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throw new IllegalArgumentException("Illegal Load: "+loadFactor); |
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if (initialCapacity==0) |
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initialCapacity = 1; |
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this.loadFactor = loadFactor; |
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table = new Entry<?,?>[initialCapacity]; |
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threshold = (int)Math.min(initialCapacity * loadFactor, MAX_ARRAY_SIZE + 1); |
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252 |
hashSeed = initHashSeed(); |
2 | 253 |
} |
254 |
||
255 |
/** |
|
256 |
* Constructs a new, empty hashtable with the specified initial capacity |
|
257 |
* and default load factor (0.75). |
|
258 |
* |
|
259 |
* @param initialCapacity the initial capacity of the hashtable. |
|
260 |
* @exception IllegalArgumentException if the initial capacity is less |
|
261 |
* than zero. |
|
262 |
*/ |
|
263 |
public Hashtable(int initialCapacity) { |
|
264 |
this(initialCapacity, 0.75f); |
|
265 |
} |
|
266 |
||
267 |
/** |
|
268 |
* Constructs a new, empty hashtable with a default initial capacity (11) |
|
269 |
* and load factor (0.75). |
|
270 |
*/ |
|
271 |
public Hashtable() { |
|
272 |
this(11, 0.75f); |
|
273 |
} |
|
274 |
||
275 |
/** |
|
276 |
* Constructs a new hashtable with the same mappings as the given |
|
277 |
* Map. The hashtable is created with an initial capacity sufficient to |
|
278 |
* hold the mappings in the given Map and a default load factor (0.75). |
|
279 |
* |
|
280 |
* @param t the map whose mappings are to be placed in this map. |
|
281 |
* @throws NullPointerException if the specified map is null. |
|
282 |
* @since 1.2 |
|
283 |
*/ |
|
284 |
public Hashtable(Map<? extends K, ? extends V> t) { |
|
285 |
this(Math.max(2*t.size(), 11), 0.75f); |
|
286 |
putAll(t); |
|
287 |
} |
|
288 |
||
289 |
/** |
|
290 |
* Returns the number of keys in this hashtable. |
|
291 |
* |
|
292 |
* @return the number of keys in this hashtable. |
|
293 |
*/ |
|
294 |
public synchronized int size() { |
|
295 |
return count; |
|
296 |
} |
|
297 |
||
298 |
/** |
|
299 |
* Tests if this hashtable maps no keys to values. |
|
300 |
* |
|
301 |
* @return <code>true</code> if this hashtable maps no keys to values; |
|
302 |
* <code>false</code> otherwise. |
|
303 |
*/ |
|
304 |
public synchronized boolean isEmpty() { |
|
305 |
return count == 0; |
|
306 |
} |
|
307 |
||
308 |
/** |
|
309 |
* Returns an enumeration of the keys in this hashtable. |
|
310 |
* |
|
311 |
* @return an enumeration of the keys in this hashtable. |
|
312 |
* @see Enumeration |
|
313 |
* @see #elements() |
|
314 |
* @see #keySet() |
|
315 |
* @see Map |
|
316 |
*/ |
|
317 |
public synchronized Enumeration<K> keys() { |
|
318 |
return this.<K>getEnumeration(KEYS); |
|
319 |
} |
|
320 |
||
321 |
/** |
|
322 |
* Returns an enumeration of the values in this hashtable. |
|
323 |
* Use the Enumeration methods on the returned object to fetch the elements |
|
324 |
* sequentially. |
|
325 |
* |
|
326 |
* @return an enumeration of the values in this hashtable. |
|
327 |
* @see java.util.Enumeration |
|
328 |
* @see #keys() |
|
329 |
* @see #values() |
|
330 |
* @see Map |
|
331 |
*/ |
|
332 |
public synchronized Enumeration<V> elements() { |
|
333 |
return this.<V>getEnumeration(VALUES); |
|
334 |
} |
|
335 |
||
336 |
/** |
|
337 |
* Tests if some key maps into the specified value in this hashtable. |
|
338 |
* This operation is more expensive than the {@link #containsKey |
|
339 |
* containsKey} method. |
|
340 |
* |
|
341 |
* <p>Note that this method is identical in functionality to |
|
342 |
* {@link #containsValue containsValue}, (which is part of the |
|
343 |
* {@link Map} interface in the collections framework). |
|
344 |
* |
|
345 |
* @param value a value to search for |
|
346 |
* @return <code>true</code> if and only if some key maps to the |
|
347 |
* <code>value</code> argument in this hashtable as |
|
348 |
* determined by the <tt>equals</tt> method; |
|
349 |
* <code>false</code> otherwise. |
|
350 |
* @exception NullPointerException if the value is <code>null</code> |
|
351 |
*/ |
|
352 |
public synchronized boolean contains(Object value) { |
|
353 |
if (value == null) { |
|
354 |
throw new NullPointerException(); |
|
355 |
} |
|
356 |
||
12448 | 357 |
Entry<?,?> tab[] = table; |
2 | 358 |
for (int i = tab.length ; i-- > 0 ;) { |
12448 | 359 |
for (Entry<?,?> e = tab[i] ; e != null ; e = e.next) { |
2 | 360 |
if (e.value.equals(value)) { |
361 |
return true; |
|
362 |
} |
|
363 |
} |
|
364 |
} |
|
365 |
return false; |
|
366 |
} |
|
367 |
||
368 |
/** |
|
369 |
* Returns true if this hashtable maps one or more keys to this value. |
|
370 |
* |
|
371 |
* <p>Note that this method is identical in functionality to {@link |
|
372 |
* #contains contains} (which predates the {@link Map} interface). |
|
373 |
* |
|
374 |
* @param value value whose presence in this hashtable is to be tested |
|
375 |
* @return <tt>true</tt> if this map maps one or more keys to the |
|
376 |
* specified value |
|
377 |
* @throws NullPointerException if the value is <code>null</code> |
|
378 |
* @since 1.2 |
|
379 |
*/ |
|
380 |
public boolean containsValue(Object value) { |
|
381 |
return contains(value); |
|
382 |
} |
|
383 |
||
384 |
/** |
|
385 |
* Tests if the specified object is a key in this hashtable. |
|
386 |
* |
|
387 |
* @param key possible key |
|
388 |
* @return <code>true</code> if and only if the specified object |
|
389 |
* is a key in this hashtable, as determined by the |
|
390 |
* <tt>equals</tt> method; <code>false</code> otherwise. |
|
391 |
* @throws NullPointerException if the key is <code>null</code> |
|
392 |
* @see #contains(Object) |
|
393 |
*/ |
|
394 |
public synchronized boolean containsKey(Object key) { |
|
12448 | 395 |
Entry<?,?> tab[] = table; |
12859
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7126277: Alternative String hashing implementation
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|
396 |
int hash = hash(key); |
2 | 397 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
12448 | 398 |
for (Entry<?,?> e = tab[index] ; e != null ; e = e.next) { |
2 | 399 |
if ((e.hash == hash) && e.key.equals(key)) { |
400 |
return true; |
|
401 |
} |
|
402 |
} |
|
403 |
return false; |
|
404 |
} |
|
405 |
||
406 |
/** |
|
407 |
* Returns the value to which the specified key is mapped, |
|
408 |
* or {@code null} if this map contains no mapping for the key. |
|
409 |
* |
|
410 |
* <p>More formally, if this map contains a mapping from a key |
|
411 |
* {@code k} to a value {@code v} such that {@code (key.equals(k))}, |
|
412 |
* then this method returns {@code v}; otherwise it returns |
|
413 |
* {@code null}. (There can be at most one such mapping.) |
|
414 |
* |
|
415 |
* @param key the key whose associated value is to be returned |
|
416 |
* @return the value to which the specified key is mapped, or |
|
417 |
* {@code null} if this map contains no mapping for the key |
|
418 |
* @throws NullPointerException if the specified key is null |
|
419 |
* @see #put(Object, Object) |
|
420 |
*/ |
|
12448 | 421 |
@SuppressWarnings("unchecked") |
2 | 422 |
public synchronized V get(Object key) { |
12448 | 423 |
Entry<?,?> tab[] = table; |
12859
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7126277: Alternative String hashing implementation
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12448
diff
changeset
|
424 |
int hash = hash(key); |
2 | 425 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
12448 | 426 |
for (Entry<?,?> e = tab[index] ; e != null ; e = e.next) { |
2 | 427 |
if ((e.hash == hash) && e.key.equals(key)) { |
12448 | 428 |
return (V)e.value; |
2 | 429 |
} |
430 |
} |
|
431 |
return null; |
|
432 |
} |
|
433 |
||
434 |
/** |
|
5466
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martin
parents:
715
diff
changeset
|
435 |
* The maximum size of array to allocate. |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
436 |
* Some VMs reserve some header words in an array. |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
437 |
* Attempts to allocate larger arrays may result in |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
438 |
* OutOfMemoryError: Requested array size exceeds VM limit |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
439 |
*/ |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
440 |
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
441 |
|
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
442 |
/** |
2 | 443 |
* Increases the capacity of and internally reorganizes this |
444 |
* hashtable, in order to accommodate and access its entries more |
|
445 |
* efficiently. This method is called automatically when the |
|
446 |
* number of keys in the hashtable exceeds this hashtable's capacity |
|
447 |
* and load factor. |
|
448 |
*/ |
|
12448 | 449 |
@SuppressWarnings("unchecked") |
2 | 450 |
protected void rehash() { |
451 |
int oldCapacity = table.length; |
|
12448 | 452 |
Entry<?,?>[] oldMap = table; |
2 | 453 |
|
5466
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
454 |
// overflow-conscious code |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
455 |
int newCapacity = (oldCapacity << 1) + 1; |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
456 |
if (newCapacity - MAX_ARRAY_SIZE > 0) { |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
457 |
if (oldCapacity == MAX_ARRAY_SIZE) |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
458 |
// Keep running with MAX_ARRAY_SIZE buckets |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
459 |
return; |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
460 |
newCapacity = MAX_ARRAY_SIZE; |
f130bb07764b
6933217: Huge arrays handled poorly in core libraries
martin
parents:
715
diff
changeset
|
461 |
} |
12448 | 462 |
Entry<?,?>[] newMap = new Entry<?,?>[newCapacity]; |
2 | 463 |
|
464 |
modCount++; |
|
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
465 |
threshold = (int)Math.min(newCapacity * loadFactor, MAX_ARRAY_SIZE + 1); |
2 | 466 |
table = newMap; |
467 |
||
468 |
for (int i = oldCapacity ; i-- > 0 ;) { |
|
12448 | 469 |
for (Entry<K,V> old = (Entry<K,V>)oldMap[i] ; old != null ; ) { |
2 | 470 |
Entry<K,V> e = old; |
471 |
old = old.next; |
|
472 |
||
473 |
int index = (e.hash & 0x7FFFFFFF) % newCapacity; |
|
12448 | 474 |
e.next = (Entry<K,V>)newMap[index]; |
2 | 475 |
newMap[index] = e; |
476 |
} |
|
477 |
} |
|
478 |
} |
|
479 |
||
16867 | 480 |
private void addEntry(int hash, K key, V value, int index) { |
481 |
modCount++; |
|
482 |
||
483 |
Entry<?,?> tab[] = table; |
|
484 |
if (count >= threshold) { |
|
485 |
// Rehash the table if the threshold is exceeded |
|
486 |
rehash(); |
|
487 |
||
488 |
tab = table; |
|
489 |
hash = hash(key); |
|
490 |
index = (hash & 0x7FFFFFFF) % tab.length; |
|
491 |
} |
|
492 |
||
493 |
// Creates the new entry. |
|
494 |
@SuppressWarnings("unchecked") |
|
495 |
Entry<K,V> e = (Entry<K,V>) tab[index]; |
|
496 |
tab[index] = new Entry<>(hash, key, value, e); |
|
497 |
count++; |
|
498 |
} |
|
499 |
||
2 | 500 |
/** |
501 |
* Maps the specified <code>key</code> to the specified |
|
502 |
* <code>value</code> in this hashtable. Neither the key nor the |
|
503 |
* value can be <code>null</code>. <p> |
|
504 |
* |
|
505 |
* The value can be retrieved by calling the <code>get</code> method |
|
506 |
* with a key that is equal to the original key. |
|
507 |
* |
|
508 |
* @param key the hashtable key |
|
509 |
* @param value the value |
|
510 |
* @return the previous value of the specified key in this hashtable, |
|
511 |
* or <code>null</code> if it did not have one |
|
512 |
* @exception NullPointerException if the key or value is |
|
513 |
* <code>null</code> |
|
514 |
* @see Object#equals(Object) |
|
515 |
* @see #get(Object) |
|
516 |
*/ |
|
517 |
public synchronized V put(K key, V value) { |
|
518 |
// Make sure the value is not null |
|
519 |
if (value == null) { |
|
520 |
throw new NullPointerException(); |
|
521 |
} |
|
522 |
||
523 |
// Makes sure the key is not already in the hashtable. |
|
12448 | 524 |
Entry<?,?> tab[] = table; |
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
525 |
int hash = hash(key); |
2 | 526 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
12448 | 527 |
@SuppressWarnings("unchecked") |
528 |
Entry<K,V> entry = (Entry<K,V>)tab[index]; |
|
529 |
for(; entry != null ; entry = entry.next) { |
|
530 |
if ((entry.hash == hash) && entry.key.equals(key)) { |
|
531 |
V old = entry.value; |
|
532 |
entry.value = value; |
|
2 | 533 |
return old; |
534 |
} |
|
535 |
} |
|
536 |
||
16867 | 537 |
addEntry(hash, key, value, index); |
2 | 538 |
return null; |
539 |
} |
|
540 |
||
541 |
/** |
|
542 |
* Removes the key (and its corresponding value) from this |
|
543 |
* hashtable. This method does nothing if the key is not in the hashtable. |
|
544 |
* |
|
545 |
* @param key the key that needs to be removed |
|
546 |
* @return the value to which the key had been mapped in this hashtable, |
|
547 |
* or <code>null</code> if the key did not have a mapping |
|
548 |
* @throws NullPointerException if the key is <code>null</code> |
|
549 |
*/ |
|
550 |
public synchronized V remove(Object key) { |
|
12448 | 551 |
Entry<?,?> tab[] = table; |
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
552 |
int hash = hash(key); |
2 | 553 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
12448 | 554 |
@SuppressWarnings("unchecked") |
555 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
556 |
for(Entry<K,V> prev = null ; e != null ; prev = e, e = e.next) { |
|
2 | 557 |
if ((e.hash == hash) && e.key.equals(key)) { |
558 |
modCount++; |
|
559 |
if (prev != null) { |
|
560 |
prev.next = e.next; |
|
561 |
} else { |
|
562 |
tab[index] = e.next; |
|
563 |
} |
|
564 |
count--; |
|
565 |
V oldValue = e.value; |
|
566 |
e.value = null; |
|
567 |
return oldValue; |
|
568 |
} |
|
569 |
} |
|
570 |
return null; |
|
571 |
} |
|
572 |
||
573 |
/** |
|
574 |
* Copies all of the mappings from the specified map to this hashtable. |
|
575 |
* These mappings will replace any mappings that this hashtable had for any |
|
576 |
* of the keys currently in the specified map. |
|
577 |
* |
|
578 |
* @param t mappings to be stored in this map |
|
579 |
* @throws NullPointerException if the specified map is null |
|
580 |
* @since 1.2 |
|
581 |
*/ |
|
582 |
public synchronized void putAll(Map<? extends K, ? extends V> t) { |
|
583 |
for (Map.Entry<? extends K, ? extends V> e : t.entrySet()) |
|
584 |
put(e.getKey(), e.getValue()); |
|
585 |
} |
|
586 |
||
587 |
/** |
|
588 |
* Clears this hashtable so that it contains no keys. |
|
589 |
*/ |
|
590 |
public synchronized void clear() { |
|
12448 | 591 |
Entry<?,?> tab[] = table; |
2 | 592 |
modCount++; |
593 |
for (int index = tab.length; --index >= 0; ) |
|
594 |
tab[index] = null; |
|
595 |
count = 0; |
|
596 |
} |
|
597 |
||
598 |
/** |
|
599 |
* Creates a shallow copy of this hashtable. All the structure of the |
|
600 |
* hashtable itself is copied, but the keys and values are not cloned. |
|
601 |
* This is a relatively expensive operation. |
|
602 |
* |
|
603 |
* @return a clone of the hashtable |
|
604 |
*/ |
|
605 |
public synchronized Object clone() { |
|
606 |
try { |
|
12448 | 607 |
Hashtable<?,?> t = (Hashtable<?,?>)super.clone(); |
608 |
t.table = new Entry<?,?>[table.length]; |
|
2 | 609 |
for (int i = table.length ; i-- > 0 ; ) { |
610 |
t.table[i] = (table[i] != null) |
|
12448 | 611 |
? (Entry<?,?>) table[i].clone() : null; |
2 | 612 |
} |
613 |
t.keySet = null; |
|
614 |
t.entrySet = null; |
|
615 |
t.values = null; |
|
616 |
t.modCount = 0; |
|
617 |
return t; |
|
618 |
} catch (CloneNotSupportedException e) { |
|
619 |
// this shouldn't happen, since we are Cloneable |
|
10419
12c063b39232
7084245: Update usages of InternalError to use exception chaining
sherman
parents:
9035
diff
changeset
|
620 |
throw new InternalError(e); |
2 | 621 |
} |
622 |
} |
|
623 |
||
624 |
/** |
|
625 |
* Returns a string representation of this <tt>Hashtable</tt> object |
|
626 |
* in the form of a set of entries, enclosed in braces and separated |
|
627 |
* by the ASCII characters "<tt>, </tt>" (comma and space). Each |
|
628 |
* entry is rendered as the key, an equals sign <tt>=</tt>, and the |
|
629 |
* associated element, where the <tt>toString</tt> method is used to |
|
630 |
* convert the key and element to strings. |
|
631 |
* |
|
632 |
* @return a string representation of this hashtable |
|
633 |
*/ |
|
634 |
public synchronized String toString() { |
|
635 |
int max = size() - 1; |
|
636 |
if (max == -1) |
|
637 |
return "{}"; |
|
638 |
||
639 |
StringBuilder sb = new StringBuilder(); |
|
640 |
Iterator<Map.Entry<K,V>> it = entrySet().iterator(); |
|
641 |
||
642 |
sb.append('{'); |
|
643 |
for (int i = 0; ; i++) { |
|
644 |
Map.Entry<K,V> e = it.next(); |
|
645 |
K key = e.getKey(); |
|
646 |
V value = e.getValue(); |
|
647 |
sb.append(key == this ? "(this Map)" : key.toString()); |
|
648 |
sb.append('='); |
|
649 |
sb.append(value == this ? "(this Map)" : value.toString()); |
|
650 |
||
651 |
if (i == max) |
|
652 |
return sb.append('}').toString(); |
|
653 |
sb.append(", "); |
|
654 |
} |
|
655 |
} |
|
656 |
||
657 |
||
658 |
private <T> Enumeration<T> getEnumeration(int type) { |
|
659 |
if (count == 0) { |
|
660 |
return Collections.emptyEnumeration(); |
|
661 |
} else { |
|
7803
56bc97d69d93
6880112: Project Coin: Port JDK core library code to use diamond operator
smarks
parents:
5506
diff
changeset
|
662 |
return new Enumerator<>(type, false); |
2 | 663 |
} |
664 |
} |
|
665 |
||
666 |
private <T> Iterator<T> getIterator(int type) { |
|
667 |
if (count == 0) { |
|
668 |
return Collections.emptyIterator(); |
|
669 |
} else { |
|
7803
56bc97d69d93
6880112: Project Coin: Port JDK core library code to use diamond operator
smarks
parents:
5506
diff
changeset
|
670 |
return new Enumerator<>(type, true); |
2 | 671 |
} |
672 |
} |
|
673 |
||
674 |
// Views |
|
675 |
||
676 |
/** |
|
677 |
* Each of these fields are initialized to contain an instance of the |
|
678 |
* appropriate view the first time this view is requested. The views are |
|
679 |
* stateless, so there's no reason to create more than one of each. |
|
680 |
*/ |
|
681 |
private transient volatile Set<K> keySet = null; |
|
682 |
private transient volatile Set<Map.Entry<K,V>> entrySet = null; |
|
683 |
private transient volatile Collection<V> values = null; |
|
684 |
||
685 |
/** |
|
686 |
* Returns a {@link Set} view of the keys contained in this map. |
|
687 |
* The set is backed by the map, so changes to the map are |
|
688 |
* reflected in the set, and vice-versa. If the map is modified |
|
689 |
* while an iteration over the set is in progress (except through |
|
690 |
* the iterator's own <tt>remove</tt> operation), the results of |
|
691 |
* the iteration are undefined. The set supports element removal, |
|
692 |
* which removes the corresponding mapping from the map, via the |
|
693 |
* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
|
694 |
* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> |
|
695 |
* operations. It does not support the <tt>add</tt> or <tt>addAll</tt> |
|
696 |
* operations. |
|
697 |
* |
|
698 |
* @since 1.2 |
|
699 |
*/ |
|
700 |
public Set<K> keySet() { |
|
701 |
if (keySet == null) |
|
702 |
keySet = Collections.synchronizedSet(new KeySet(), this); |
|
703 |
return keySet; |
|
704 |
} |
|
705 |
||
706 |
private class KeySet extends AbstractSet<K> { |
|
707 |
public Iterator<K> iterator() { |
|
708 |
return getIterator(KEYS); |
|
709 |
} |
|
710 |
public int size() { |
|
711 |
return count; |
|
712 |
} |
|
713 |
public boolean contains(Object o) { |
|
714 |
return containsKey(o); |
|
715 |
} |
|
716 |
public boolean remove(Object o) { |
|
717 |
return Hashtable.this.remove(o) != null; |
|
718 |
} |
|
719 |
public void clear() { |
|
720 |
Hashtable.this.clear(); |
|
721 |
} |
|
722 |
} |
|
723 |
||
724 |
/** |
|
725 |
* Returns a {@link Set} view of the mappings contained in this map. |
|
726 |
* The set is backed by the map, so changes to the map are |
|
727 |
* reflected in the set, and vice-versa. If the map is modified |
|
728 |
* while an iteration over the set is in progress (except through |
|
729 |
* the iterator's own <tt>remove</tt> operation, or through the |
|
730 |
* <tt>setValue</tt> operation on a map entry returned by the |
|
731 |
* iterator) the results of the iteration are undefined. The set |
|
732 |
* supports element removal, which removes the corresponding |
|
733 |
* mapping from the map, via the <tt>Iterator.remove</tt>, |
|
734 |
* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and |
|
735 |
* <tt>clear</tt> operations. It does not support the |
|
736 |
* <tt>add</tt> or <tt>addAll</tt> operations. |
|
737 |
* |
|
738 |
* @since 1.2 |
|
739 |
*/ |
|
740 |
public Set<Map.Entry<K,V>> entrySet() { |
|
741 |
if (entrySet==null) |
|
742 |
entrySet = Collections.synchronizedSet(new EntrySet(), this); |
|
743 |
return entrySet; |
|
744 |
} |
|
745 |
||
746 |
private class EntrySet extends AbstractSet<Map.Entry<K,V>> { |
|
747 |
public Iterator<Map.Entry<K,V>> iterator() { |
|
748 |
return getIterator(ENTRIES); |
|
749 |
} |
|
750 |
||
751 |
public boolean add(Map.Entry<K,V> o) { |
|
752 |
return super.add(o); |
|
753 |
} |
|
754 |
||
755 |
public boolean contains(Object o) { |
|
756 |
if (!(o instanceof Map.Entry)) |
|
757 |
return false; |
|
12448 | 758 |
Map.Entry<?,?> entry = (Map.Entry<?,?>)o; |
2 | 759 |
Object key = entry.getKey(); |
12448 | 760 |
Entry<?,?>[] tab = table; |
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
761 |
int hash = hash(key); |
2 | 762 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
763 |
||
12448 | 764 |
for (Entry<?,?> e = tab[index]; e != null; e = e.next) |
2 | 765 |
if (e.hash==hash && e.equals(entry)) |
766 |
return true; |
|
767 |
return false; |
|
768 |
} |
|
769 |
||
770 |
public boolean remove(Object o) { |
|
771 |
if (!(o instanceof Map.Entry)) |
|
772 |
return false; |
|
12448 | 773 |
Map.Entry<?,?> entry = (Map.Entry<?,?>) o; |
774 |
Object key = entry.getKey(); |
|
775 |
Entry<?,?>[] tab = table; |
|
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
776 |
int hash = hash(key); |
2 | 777 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
778 |
||
12448 | 779 |
@SuppressWarnings("unchecked") |
780 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
781 |
for(Entry<K,V> prev = null; e != null; prev = e, e = e.next) { |
|
2 | 782 |
if (e.hash==hash && e.equals(entry)) { |
783 |
modCount++; |
|
784 |
if (prev != null) |
|
785 |
prev.next = e.next; |
|
786 |
else |
|
787 |
tab[index] = e.next; |
|
788 |
||
789 |
count--; |
|
790 |
e.value = null; |
|
791 |
return true; |
|
792 |
} |
|
793 |
} |
|
794 |
return false; |
|
795 |
} |
|
796 |
||
797 |
public int size() { |
|
798 |
return count; |
|
799 |
} |
|
800 |
||
801 |
public void clear() { |
|
802 |
Hashtable.this.clear(); |
|
803 |
} |
|
804 |
} |
|
805 |
||
806 |
/** |
|
807 |
* Returns a {@link Collection} view of the values contained in this map. |
|
808 |
* The collection is backed by the map, so changes to the map are |
|
809 |
* reflected in the collection, and vice-versa. If the map is |
|
810 |
* modified while an iteration over the collection is in progress |
|
811 |
* (except through the iterator's own <tt>remove</tt> operation), |
|
812 |
* the results of the iteration are undefined. The collection |
|
813 |
* supports element removal, which removes the corresponding |
|
814 |
* mapping from the map, via the <tt>Iterator.remove</tt>, |
|
815 |
* <tt>Collection.remove</tt>, <tt>removeAll</tt>, |
|
816 |
* <tt>retainAll</tt> and <tt>clear</tt> operations. It does not |
|
817 |
* support the <tt>add</tt> or <tt>addAll</tt> operations. |
|
818 |
* |
|
819 |
* @since 1.2 |
|
820 |
*/ |
|
821 |
public Collection<V> values() { |
|
822 |
if (values==null) |
|
823 |
values = Collections.synchronizedCollection(new ValueCollection(), |
|
824 |
this); |
|
825 |
return values; |
|
826 |
} |
|
827 |
||
828 |
private class ValueCollection extends AbstractCollection<V> { |
|
829 |
public Iterator<V> iterator() { |
|
830 |
return getIterator(VALUES); |
|
831 |
} |
|
832 |
public int size() { |
|
833 |
return count; |
|
834 |
} |
|
835 |
public boolean contains(Object o) { |
|
836 |
return containsValue(o); |
|
837 |
} |
|
838 |
public void clear() { |
|
839 |
Hashtable.this.clear(); |
|
840 |
} |
|
841 |
} |
|
842 |
||
843 |
// Comparison and hashing |
|
844 |
||
845 |
/** |
|
846 |
* Compares the specified Object with this Map for equality, |
|
847 |
* as per the definition in the Map interface. |
|
848 |
* |
|
849 |
* @param o object to be compared for equality with this hashtable |
|
850 |
* @return true if the specified Object is equal to this Map |
|
851 |
* @see Map#equals(Object) |
|
852 |
* @since 1.2 |
|
853 |
*/ |
|
854 |
public synchronized boolean equals(Object o) { |
|
855 |
if (o == this) |
|
856 |
return true; |
|
857 |
||
858 |
if (!(o instanceof Map)) |
|
859 |
return false; |
|
12448 | 860 |
Map<?,?> t = (Map<?,?>) o; |
2 | 861 |
if (t.size() != size()) |
862 |
return false; |
|
863 |
||
864 |
try { |
|
865 |
Iterator<Map.Entry<K,V>> i = entrySet().iterator(); |
|
866 |
while (i.hasNext()) { |
|
867 |
Map.Entry<K,V> e = i.next(); |
|
868 |
K key = e.getKey(); |
|
869 |
V value = e.getValue(); |
|
870 |
if (value == null) { |
|
871 |
if (!(t.get(key)==null && t.containsKey(key))) |
|
872 |
return false; |
|
873 |
} else { |
|
874 |
if (!value.equals(t.get(key))) |
|
875 |
return false; |
|
876 |
} |
|
877 |
} |
|
878 |
} catch (ClassCastException unused) { |
|
879 |
return false; |
|
880 |
} catch (NullPointerException unused) { |
|
881 |
return false; |
|
882 |
} |
|
883 |
||
884 |
return true; |
|
885 |
} |
|
886 |
||
887 |
/** |
|
888 |
* Returns the hash code value for this Map as per the definition in the |
|
889 |
* Map interface. |
|
890 |
* |
|
891 |
* @see Map#hashCode() |
|
892 |
* @since 1.2 |
|
893 |
*/ |
|
894 |
public synchronized int hashCode() { |
|
895 |
/* |
|
896 |
* This code detects the recursion caused by computing the hash code |
|
897 |
* of a self-referential hash table and prevents the stack overflow |
|
898 |
* that would otherwise result. This allows certain 1.1-era |
|
899 |
* applets with self-referential hash tables to work. This code |
|
900 |
* abuses the loadFactor field to do double-duty as a hashCode |
|
901 |
* in progress flag, so as not to worsen the space performance. |
|
902 |
* A negative load factor indicates that hash code computation is |
|
903 |
* in progress. |
|
904 |
*/ |
|
905 |
int h = 0; |
|
906 |
if (count == 0 || loadFactor < 0) |
|
907 |
return h; // Returns zero |
|
908 |
||
909 |
loadFactor = -loadFactor; // Mark hashCode computation in progress |
|
12448 | 910 |
Entry<?,?>[] tab = table; |
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
911 |
for (Entry<?,?> entry : tab) { |
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
912 |
while (entry != null) { |
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
913 |
h += entry.hashCode(); |
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
914 |
entry = entry.next; |
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
915 |
} |
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
916 |
} |
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
917 |
|
2 | 918 |
loadFactor = -loadFactor; // Mark hashCode computation complete |
919 |
||
920 |
return h; |
|
921 |
} |
|
922 |
||
16867 | 923 |
@Override |
924 |
public synchronized V getOrDefault(Object key, V defaultValue) { |
|
925 |
V result = get(key); |
|
926 |
return (null == result) ? defaultValue : result; |
|
927 |
} |
|
928 |
||
929 |
@Override |
|
930 |
public synchronized void forEach(BiConsumer<? super K, ? super V> action) { |
|
931 |
Objects.requireNonNull(action); // explicit check required in case |
|
932 |
// table is empty. |
|
933 |
Entry<?,?>[] tab = table; |
|
934 |
for (Entry<?,?> entry : tab) { |
|
935 |
while (entry != null) { |
|
936 |
action.accept((K)entry.key, (V)entry.value); |
|
937 |
entry = entry.next; |
|
938 |
} |
|
939 |
} |
|
940 |
} |
|
941 |
||
942 |
@Override |
|
943 |
public synchronized void replaceAll( |
|
944 |
BiFunction<? super K, ? super V, ? extends V> function) { |
|
945 |
Map.super.replaceAll(function); |
|
946 |
} |
|
947 |
||
948 |
@Override |
|
949 |
public synchronized V putIfAbsent(K key, V value) { |
|
950 |
Objects.requireNonNull(value); |
|
951 |
||
952 |
// Makes sure the key is not already in the hashtable. |
|
953 |
Entry<?,?> tab[] = table; |
|
954 |
int hash = hash(key); |
|
955 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
956 |
@SuppressWarnings("unchecked") |
|
957 |
Entry<K,V> entry = (Entry<K,V>)tab[index]; |
|
958 |
for (; entry != null; entry = entry.next) { |
|
959 |
if ((entry.hash == hash) && entry.key.equals(key)) { |
|
960 |
V old = entry.value; |
|
961 |
if (old == null) { |
|
962 |
entry.value = value; |
|
963 |
} |
|
964 |
return old; |
|
965 |
} |
|
966 |
} |
|
967 |
||
968 |
addEntry(hash, key, value, index); |
|
969 |
return null; |
|
970 |
} |
|
971 |
||
972 |
@Override |
|
973 |
public synchronized boolean remove(Object key, Object value) { |
|
974 |
Objects.requireNonNull(value); |
|
975 |
||
976 |
Entry<?,?> tab[] = table; |
|
977 |
int hash = hash(key); |
|
978 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
979 |
@SuppressWarnings("unchecked") |
|
980 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
981 |
for (Entry<K,V> prev = null; e != null; prev = e, e = e.next) { |
|
982 |
if ((e.hash == hash) && e.key.equals(key) && e.value.equals(value)) { |
|
983 |
modCount++; |
|
984 |
if (prev != null) { |
|
985 |
prev.next = e.next; |
|
986 |
} else { |
|
987 |
tab[index] = e.next; |
|
988 |
} |
|
989 |
count--; |
|
990 |
e.value = null; |
|
991 |
return true; |
|
992 |
} |
|
993 |
} |
|
994 |
return false; |
|
995 |
} |
|
996 |
||
997 |
@Override |
|
998 |
public synchronized boolean replace(K key, V oldValue, V newValue) { |
|
999 |
Entry<?,?> tab[] = table; |
|
1000 |
int hash = hash(key); |
|
1001 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
1002 |
@SuppressWarnings("unchecked") |
|
1003 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
1004 |
for (; e != null; e = e.next) { |
|
1005 |
if ((e.hash == hash) && e.key.equals(key)) { |
|
1006 |
if (e.value.equals(oldValue)) { |
|
1007 |
e.value = newValue; |
|
1008 |
return true; |
|
1009 |
} else { |
|
1010 |
return false; |
|
1011 |
} |
|
1012 |
} |
|
1013 |
} |
|
1014 |
return false; |
|
1015 |
} |
|
1016 |
||
1017 |
@Override |
|
1018 |
public synchronized V replace(K key, V value) { |
|
1019 |
Entry<?,?> tab[] = table; |
|
1020 |
int hash = hash(key); |
|
1021 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
1022 |
@SuppressWarnings("unchecked") |
|
1023 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
1024 |
for (; e != null; e = e.next) { |
|
1025 |
if ((e.hash == hash) && e.key.equals(key)) { |
|
1026 |
V oldValue = e.value; |
|
1027 |
e.value = value; |
|
1028 |
return oldValue; |
|
1029 |
} |
|
1030 |
} |
|
1031 |
return null; |
|
1032 |
} |
|
1033 |
||
1034 |
@Override |
|
1035 |
public synchronized V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) { |
|
1036 |
Objects.requireNonNull(mappingFunction); |
|
1037 |
||
1038 |
Entry<?,?> tab[] = table; |
|
1039 |
int hash = hash(key); |
|
1040 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
1041 |
@SuppressWarnings("unchecked") |
|
1042 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
1043 |
for (; e != null; e = e.next) { |
|
1044 |
if (e.hash == hash && e.key.equals(key)) { |
|
1045 |
// Hashtable not accept null value |
|
1046 |
return e.value; |
|
1047 |
} |
|
1048 |
} |
|
1049 |
||
1050 |
V newValue = mappingFunction.apply(key); |
|
1051 |
if (newValue != null) { |
|
1052 |
addEntry(hash, key, newValue, index); |
|
1053 |
} |
|
1054 |
||
1055 |
return newValue; |
|
1056 |
} |
|
1057 |
||
1058 |
@Override |
|
1059 |
public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { |
|
1060 |
Objects.requireNonNull(remappingFunction); |
|
1061 |
||
1062 |
Entry<?,?> tab[] = table; |
|
1063 |
int hash = hash(key); |
|
1064 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
1065 |
@SuppressWarnings("unchecked") |
|
1066 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
1067 |
for (Entry<K,V> prev = null; e != null; prev = e, e = e.next) { |
|
1068 |
if (e.hash == hash && e.key.equals(key)) { |
|
1069 |
V newValue = remappingFunction.apply(key, e.value); |
|
1070 |
if (newValue == null) { |
|
1071 |
modCount++; |
|
1072 |
if (prev != null) { |
|
1073 |
prev.next = e.next; |
|
1074 |
} else { |
|
1075 |
tab[index] = e.next; |
|
1076 |
} |
|
1077 |
count--; |
|
1078 |
} else { |
|
1079 |
e.value = newValue; |
|
1080 |
} |
|
1081 |
return newValue; |
|
1082 |
} |
|
1083 |
} |
|
1084 |
return null; |
|
1085 |
} |
|
1086 |
||
1087 |
@Override |
|
1088 |
public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { |
|
1089 |
Objects.requireNonNull(remappingFunction); |
|
1090 |
||
1091 |
Entry<?,?> tab[] = table; |
|
1092 |
int hash = hash(key); |
|
1093 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
1094 |
@SuppressWarnings("unchecked") |
|
1095 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
1096 |
for (Entry<K,V> prev = null; e != null; prev = e, e = e.next) { |
|
1097 |
if (e.hash == hash && Objects.equals(e.key, key)) { |
|
1098 |
V newValue = remappingFunction.apply(key, e.value); |
|
1099 |
if (newValue == null) { |
|
1100 |
modCount++; |
|
1101 |
if (prev != null) { |
|
1102 |
prev.next = e.next; |
|
1103 |
} else { |
|
1104 |
tab[index] = e.next; |
|
1105 |
} |
|
1106 |
count--; |
|
1107 |
} else { |
|
1108 |
e.value = newValue; |
|
1109 |
} |
|
1110 |
return newValue; |
|
1111 |
} |
|
1112 |
} |
|
1113 |
||
1114 |
V newValue = remappingFunction.apply(key, null); |
|
1115 |
if (newValue != null) { |
|
1116 |
addEntry(hash, key, newValue, index); |
|
1117 |
} |
|
1118 |
||
1119 |
return newValue; |
|
1120 |
} |
|
1121 |
||
1122 |
@Override |
|
1123 |
public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) { |
|
1124 |
Objects.requireNonNull(remappingFunction); |
|
1125 |
||
1126 |
Entry<?,?> tab[] = table; |
|
1127 |
int hash = hash(key); |
|
1128 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
|
1129 |
@SuppressWarnings("unchecked") |
|
1130 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
1131 |
for (Entry<K,V> prev = null; e != null; prev = e, e = e.next) { |
|
1132 |
if (e.hash == hash && e.key.equals(key)) { |
|
1133 |
V newValue = remappingFunction.apply(e.value, value); |
|
1134 |
if (newValue == null) { |
|
1135 |
modCount++; |
|
1136 |
if (prev != null) { |
|
1137 |
prev.next = e.next; |
|
1138 |
} else { |
|
1139 |
tab[index] = e.next; |
|
1140 |
} |
|
1141 |
count--; |
|
1142 |
} else { |
|
1143 |
e.value = newValue; |
|
1144 |
} |
|
1145 |
return newValue; |
|
1146 |
} |
|
1147 |
} |
|
1148 |
||
1149 |
if (value != null) { |
|
1150 |
addEntry(hash, key, value, index); |
|
1151 |
} |
|
1152 |
||
1153 |
return value; |
|
1154 |
} |
|
1155 |
||
2 | 1156 |
/** |
1157 |
* Save the state of the Hashtable to a stream (i.e., serialize it). |
|
1158 |
* |
|
1159 |
* @serialData The <i>capacity</i> of the Hashtable (the length of the |
|
1160 |
* bucket array) is emitted (int), followed by the |
|
1161 |
* <i>size</i> of the Hashtable (the number of key-value |
|
1162 |
* mappings), followed by the key (Object) and value (Object) |
|
1163 |
* for each key-value mapping represented by the Hashtable |
|
1164 |
* The key-value mappings are emitted in no particular order. |
|
1165 |
*/ |
|
8394 | 1166 |
private void writeObject(java.io.ObjectOutputStream s) |
1167 |
throws IOException { |
|
1168 |
Entry<Object, Object> entryStack = null; |
|
1169 |
||
1170 |
synchronized (this) { |
|
1171 |
// Write out the length, threshold, loadfactor |
|
1172 |
s.defaultWriteObject(); |
|
1173 |
||
1174 |
// Write out length, count of elements |
|
1175 |
s.writeInt(table.length); |
|
1176 |
s.writeInt(count); |
|
2 | 1177 |
|
8394 | 1178 |
// Stack copies of the entries in the table |
1179 |
for (int index = 0; index < table.length; index++) { |
|
12448 | 1180 |
Entry<?,?> entry = table[index]; |
2 | 1181 |
|
8394 | 1182 |
while (entry != null) { |
1183 |
entryStack = |
|
1184 |
new Entry<>(0, entry.key, entry.value, entryStack); |
|
1185 |
entry = entry.next; |
|
1186 |
} |
|
2 | 1187 |
} |
1188 |
} |
|
8394 | 1189 |
|
1190 |
// Write out the key/value objects from the stacked entries |
|
1191 |
while (entryStack != null) { |
|
1192 |
s.writeObject(entryStack.key); |
|
1193 |
s.writeObject(entryStack.value); |
|
1194 |
entryStack = entryStack.next; |
|
1195 |
} |
|
2 | 1196 |
} |
1197 |
||
1198 |
/** |
|
1199 |
* Reconstitute the Hashtable from a stream (i.e., deserialize it). |
|
1200 |
*/ |
|
1201 |
private void readObject(java.io.ObjectInputStream s) |
|
1202 |
throws IOException, ClassNotFoundException |
|
1203 |
{ |
|
1204 |
// Read in the length, threshold, and loadfactor |
|
1205 |
s.defaultReadObject(); |
|
1206 |
||
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1207 |
// set hashMask |
17939
bd750ec19d82
8005698: Handle Frequent HashMap Collisions with Balanced Trees
bchristi
parents:
16867
diff
changeset
|
1208 |
if (Holder.USE_HASHSEED) { |
bd750ec19d82
8005698: Handle Frequent HashMap Collisions with Balanced Trees
bchristi
parents:
16867
diff
changeset
|
1209 |
Holder.UNSAFE.putIntVolatile(this, Holder.HASHSEED_OFFSET, |
bd750ec19d82
8005698: Handle Frequent HashMap Collisions with Balanced Trees
bchristi
parents:
16867
diff
changeset
|
1210 |
sun.misc.Hashing.randomHashSeed(this)); |
bd750ec19d82
8005698: Handle Frequent HashMap Collisions with Balanced Trees
bchristi
parents:
16867
diff
changeset
|
1211 |
} |
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1212 |
|
2 | 1213 |
// Read the original length of the array and number of elements |
1214 |
int origlength = s.readInt(); |
|
1215 |
int elements = s.readInt(); |
|
1216 |
||
1217 |
// Compute new size with a bit of room 5% to grow but |
|
1218 |
// no larger than the original size. Make the length |
|
1219 |
// odd if it's large enough, this helps distribute the entries. |
|
1220 |
// Guard against the length ending up zero, that's not valid. |
|
1221 |
int length = (int)(elements * loadFactor) + (elements / 20) + 3; |
|
1222 |
if (length > elements && (length & 1) == 0) |
|
1223 |
length--; |
|
1224 |
if (origlength > 0 && length > origlength) |
|
1225 |
length = origlength; |
|
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1226 |
table = new Entry<?,?>[length]; |
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1227 |
threshold = (int)Math.min(length * loadFactor, MAX_ARRAY_SIZE + 1); |
2 | 1228 |
count = 0; |
1229 |
||
1230 |
// Read the number of elements and then all the key/value objects |
|
1231 |
for (; elements > 0; elements--) { |
|
12448 | 1232 |
@SuppressWarnings("unchecked") |
1233 |
K key = (K)s.readObject(); |
|
1234 |
@SuppressWarnings("unchecked") |
|
1235 |
V value = (V)s.readObject(); |
|
2 | 1236 |
// synch could be eliminated for performance |
1237 |
reconstitutionPut(table, key, value); |
|
1238 |
} |
|
1239 |
} |
|
1240 |
||
1241 |
/** |
|
1242 |
* The put method used by readObject. This is provided because put |
|
1243 |
* is overridable and should not be called in readObject since the |
|
1244 |
* subclass will not yet be initialized. |
|
1245 |
* |
|
1246 |
* <p>This differs from the regular put method in several ways. No |
|
1247 |
* checking for rehashing is necessary since the number of elements |
|
1248 |
* initially in the table is known. The modCount is not incremented |
|
1249 |
* because we are creating a new instance. Also, no return value |
|
1250 |
* is needed. |
|
1251 |
*/ |
|
12448 | 1252 |
private void reconstitutionPut(Entry<?,?>[] tab, K key, V value) |
2 | 1253 |
throws StreamCorruptedException |
1254 |
{ |
|
1255 |
if (value == null) { |
|
1256 |
throw new java.io.StreamCorruptedException(); |
|
1257 |
} |
|
1258 |
// Makes sure the key is not already in the hashtable. |
|
1259 |
// This should not happen in deserialized version. |
|
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1260 |
int hash = hash(key); |
2 | 1261 |
int index = (hash & 0x7FFFFFFF) % tab.length; |
12448 | 1262 |
for (Entry<?,?> e = tab[index] ; e != null ; e = e.next) { |
2 | 1263 |
if ((e.hash == hash) && e.key.equals(key)) { |
1264 |
throw new java.io.StreamCorruptedException(); |
|
1265 |
} |
|
1266 |
} |
|
1267 |
// Creates the new entry. |
|
12448 | 1268 |
@SuppressWarnings("unchecked") |
1269 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
7803
56bc97d69d93
6880112: Project Coin: Port JDK core library code to use diamond operator
smarks
parents:
5506
diff
changeset
|
1270 |
tab[index] = new Entry<>(hash, key, value, e); |
2 | 1271 |
count++; |
1272 |
} |
|
1273 |
||
1274 |
/** |
|
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1275 |
* Hashtable bucket collision list entry |
2 | 1276 |
*/ |
1277 |
private static class Entry<K,V> implements Map.Entry<K,V> { |
|
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1278 |
final int hash; |
13018 | 1279 |
final K key; |
2 | 1280 |
V value; |
1281 |
Entry<K,V> next; |
|
1282 |
||
1283 |
protected Entry(int hash, K key, V value, Entry<K,V> next) { |
|
1284 |
this.hash = hash; |
|
12859
c44b88bb9b5e
7126277: Alternative String hashing implementation
mduigou
parents:
12448
diff
changeset
|
1285 |
this.key = key; |
2 | 1286 |
this.value = value; |
1287 |
this.next = next; |
|
1288 |
} |
|
1289 |
||
12448 | 1290 |
@SuppressWarnings("unchecked") |
2 | 1291 |
protected Object clone() { |
7803
56bc97d69d93
6880112: Project Coin: Port JDK core library code to use diamond operator
smarks
parents:
5506
diff
changeset
|
1292 |
return new Entry<>(hash, key, value, |
2 | 1293 |
(next==null ? null : (Entry<K,V>) next.clone())); |
1294 |
} |
|
1295 |
||
1296 |
// Map.Entry Ops |
|
1297 |
||
1298 |
public K getKey() { |
|
1299 |
return key; |
|
1300 |
} |
|
1301 |
||
1302 |
public V getValue() { |
|
1303 |
return value; |
|
1304 |
} |
|
1305 |
||
1306 |
public V setValue(V value) { |
|
1307 |
if (value == null) |
|
1308 |
throw new NullPointerException(); |
|
1309 |
||
1310 |
V oldValue = this.value; |
|
1311 |
this.value = value; |
|
1312 |
return oldValue; |
|
1313 |
} |
|
1314 |
||
1315 |
public boolean equals(Object o) { |
|
1316 |
if (!(o instanceof Map.Entry)) |
|
1317 |
return false; |
|
12448 | 1318 |
Map.Entry<?,?> e = (Map.Entry<?,?>)o; |
2 | 1319 |
|
1320 |
return (key==null ? e.getKey()==null : key.equals(e.getKey())) && |
|
1321 |
(value==null ? e.getValue()==null : value.equals(e.getValue())); |
|
1322 |
} |
|
1323 |
||
1324 |
public int hashCode() { |
|
14188
82c029bd5f70
8000955: Hashtable.Entry.hashCode() does not conform to Map.Entry.hashCode() defined behaviour
ngmr
parents:
13018
diff
changeset
|
1325 |
return (Objects.hashCode(key) ^ Objects.hashCode(value)); |
2 | 1326 |
} |
1327 |
||
1328 |
public String toString() { |
|
1329 |
return key.toString()+"="+value.toString(); |
|
1330 |
} |
|
1331 |
} |
|
1332 |
||
1333 |
// Types of Enumerations/Iterations |
|
1334 |
private static final int KEYS = 0; |
|
1335 |
private static final int VALUES = 1; |
|
1336 |
private static final int ENTRIES = 2; |
|
1337 |
||
1338 |
/** |
|
1339 |
* A hashtable enumerator class. This class implements both the |
|
1340 |
* Enumeration and Iterator interfaces, but individual instances |
|
1341 |
* can be created with the Iterator methods disabled. This is necessary |
|
1342 |
* to avoid unintentionally increasing the capabilities granted a user |
|
1343 |
* by passing an Enumeration. |
|
1344 |
*/ |
|
1345 |
private class Enumerator<T> implements Enumeration<T>, Iterator<T> { |
|
12448 | 1346 |
Entry<?,?>[] table = Hashtable.this.table; |
2 | 1347 |
int index = table.length; |
12448 | 1348 |
Entry<?,?> entry = null; |
1349 |
Entry<?,?> lastReturned = null; |
|
2 | 1350 |
int type; |
1351 |
||
1352 |
/** |
|
1353 |
* Indicates whether this Enumerator is serving as an Iterator |
|
1354 |
* or an Enumeration. (true -> Iterator). |
|
1355 |
*/ |
|
1356 |
boolean iterator; |
|
1357 |
||
1358 |
/** |
|
1359 |
* The modCount value that the iterator believes that the backing |
|
1360 |
* Hashtable should have. If this expectation is violated, the iterator |
|
1361 |
* has detected concurrent modification. |
|
1362 |
*/ |
|
1363 |
protected int expectedModCount = modCount; |
|
1364 |
||
1365 |
Enumerator(int type, boolean iterator) { |
|
1366 |
this.type = type; |
|
1367 |
this.iterator = iterator; |
|
1368 |
} |
|
1369 |
||
1370 |
public boolean hasMoreElements() { |
|
12448 | 1371 |
Entry<?,?> e = entry; |
2 | 1372 |
int i = index; |
12448 | 1373 |
Entry<?,?>[] t = table; |
2 | 1374 |
/* Use locals for faster loop iteration */ |
1375 |
while (e == null && i > 0) { |
|
1376 |
e = t[--i]; |
|
1377 |
} |
|
1378 |
entry = e; |
|
1379 |
index = i; |
|
1380 |
return e != null; |
|
1381 |
} |
|
1382 |
||
12448 | 1383 |
@SuppressWarnings("unchecked") |
2 | 1384 |
public T nextElement() { |
12448 | 1385 |
Entry<?,?> et = entry; |
2 | 1386 |
int i = index; |
12448 | 1387 |
Entry<?,?>[] t = table; |
2 | 1388 |
/* Use locals for faster loop iteration */ |
1389 |
while (et == null && i > 0) { |
|
1390 |
et = t[--i]; |
|
1391 |
} |
|
1392 |
entry = et; |
|
1393 |
index = i; |
|
1394 |
if (et != null) { |
|
12448 | 1395 |
Entry<?,?> e = lastReturned = entry; |
2 | 1396 |
entry = e.next; |
1397 |
return type == KEYS ? (T)e.key : (type == VALUES ? (T)e.value : (T)e); |
|
1398 |
} |
|
1399 |
throw new NoSuchElementException("Hashtable Enumerator"); |
|
1400 |
} |
|
1401 |
||
1402 |
// Iterator methods |
|
1403 |
public boolean hasNext() { |
|
1404 |
return hasMoreElements(); |
|
1405 |
} |
|
1406 |
||
1407 |
public T next() { |
|
1408 |
if (modCount != expectedModCount) |
|
1409 |
throw new ConcurrentModificationException(); |
|
1410 |
return nextElement(); |
|
1411 |
} |
|
1412 |
||
1413 |
public void remove() { |
|
1414 |
if (!iterator) |
|
1415 |
throw new UnsupportedOperationException(); |
|
1416 |
if (lastReturned == null) |
|
1417 |
throw new IllegalStateException("Hashtable Enumerator"); |
|
1418 |
if (modCount != expectedModCount) |
|
1419 |
throw new ConcurrentModificationException(); |
|
1420 |
||
1421 |
synchronized(Hashtable.this) { |
|
12448 | 1422 |
Entry<?,?>[] tab = Hashtable.this.table; |
2 | 1423 |
int index = (lastReturned.hash & 0x7FFFFFFF) % tab.length; |
1424 |
||
12448 | 1425 |
@SuppressWarnings("unchecked") |
1426 |
Entry<K,V> e = (Entry<K,V>)tab[index]; |
|
1427 |
for(Entry<K,V> prev = null; e != null; prev = e, e = e.next) { |
|
2 | 1428 |
if (e == lastReturned) { |
1429 |
modCount++; |
|
1430 |
expectedModCount++; |
|
1431 |
if (prev == null) |
|
1432 |
tab[index] = e.next; |
|
1433 |
else |
|
1434 |
prev.next = e.next; |
|
1435 |
count--; |
|
1436 |
lastReturned = null; |
|
1437 |
return; |
|
1438 |
} |
|
1439 |
} |
|
1440 |
throw new ConcurrentModificationException(); |
|
1441 |
} |
|
1442 |
} |
|
1443 |
} |
|
1444 |
} |