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/* |
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* %W% %E% |
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* Copyright 1997-2006 Sun Microsystems, Inc. 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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* Copyright 2004 Sun Microsystems, Inc. All rights reserved. |
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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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. Sun designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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* CA 95054 USA or visit www.sun.com if you need additional information or |
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* have any questions. |
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*/ |
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|
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package java.util; |
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/** |
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* This class provides a skeletal implementation of the <tt>Map</tt> |
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* interface, to minimize the effort required to implement this interface. <p> |
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* interface, to minimize the effort required to implement this interface. |
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* |
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* To implement an unmodifiable map, the programmer needs only to extend this |
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* <p>To implement an unmodifiable map, the programmer needs only to extend this |
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* class and provide an implementation for the <tt>entrySet</tt> method, which |
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* returns a set-view of the map's mappings. Typically, the returned set |
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* will, in turn, be implemented atop <tt>AbstractSet</tt>. This set should |
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* not support the <tt>add</tt> or <tt>remove</tt> methods, and its iterator |
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* should not support the <tt>remove</tt> method.<p> |
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* should not support the <tt>remove</tt> method. |
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* |
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* To implement a modifiable map, the programmer must additionally override |
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* <p>To implement a modifiable map, the programmer must additionally override |
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* this class's <tt>put</tt> method (which otherwise throws an |
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* <tt>UnsupportedOperationException</tt>), and the iterator returned by |
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* <tt>entrySet().iterator()</tt> must additionally implement its |
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* <tt>remove</tt> method.<p> |
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* <tt>remove</tt> method. |
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* |
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* The programmer should generally provide a void (no argument) and map |
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* <p>The programmer should generally provide a void (no argument) and map |
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* constructor, as per the recommendation in the <tt>Map</tt> interface |
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* specification.<p> |
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* specification. |
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* |
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* The documentation for each non-abstract methods in this class describes its |
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* <p>The documentation for each non-abstract method in this class describes its |
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* implementation in detail. Each of these methods may be overridden if the |
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* map being implemented admits a more efficient implementation.<p> |
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* map being implemented admits a more efficient implementation. |
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* |
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* This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @param <K> the type of keys maintained by this map |
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* @param <V> the type of mapped values |
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* |
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* @author Josh Bloch |
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* @author Neal Gafter |
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* @version %I%, %G% |
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// Query Operations |
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|
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/** |
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* Returns the number of key-value mappings in this map. If the map |
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* contains more than <tt>Integer.MAX_VALUE</tt> elements, returns |
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* <tt>Integer.MAX_VALUE</tt>.<p> |
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* |
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* This implementation returns <tt>entrySet().size()</tt>. |
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* {@inheritDoc} |
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* |
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* @return the number of key-value mappings in this map. |
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* <p>This implementation returns <tt>entrySet().size()</tt>. |
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*/ |
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public int size() { |
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return entrySet().size(); |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this map contains no key-value mappings. <p> |
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* |
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* This implementation returns <tt>size() == 0</tt>. |
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* {@inheritDoc} |
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* |
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* @return <tt>true</tt> if this map contains no key-value mappings. |
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* <p>This implementation returns <tt>size() == 0</tt>. |
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*/ |
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public boolean isEmpty() { |
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return size() == 0; |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this map maps one or more keys to this value. |
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* More formally, returns <tt>true</tt> if and only if this map contains |
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* at least one mapping to a value <tt>v</tt> such that <tt>(value==null ? |
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* v==null : value.equals(v))</tt>. This operation will probably require |
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* time linear in the map size for most implementations of map.<p> |
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* |
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* This implementation iterates over entrySet() searching for an entry |
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* with the specified value. If such an entry is found, <tt>true</tt> is |
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* returned. If the iteration terminates without finding such an entry, |
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* <tt>false</tt> is returned. Note that this implementation requires |
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* linear time in the size of the map. |
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* |
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* @param value value whose presence in this map is to be tested. |
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* |
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* @return <tt>true</tt> if this map maps one or more keys to this value. |
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* {@inheritDoc} |
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* |
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* <p>This implementation iterates over <tt>entrySet()</tt> searching |
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* for an entry with the specified value. If such an entry is found, |
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* <tt>true</tt> is returned. If the iteration terminates without |
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* finding such an entry, <tt>false</tt> is returned. Note that this |
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* implementation requires linear time in the size of the map. |
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* |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public boolean containsValue(Object value) { |
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Iterator<Entry<K,V>> i = entrySet().iterator(); |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this map contains a mapping for the specified |
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* key. <p> |
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* {@inheritDoc} |
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* |
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* <p>This implementation iterates over <tt>entrySet()</tt> searching |
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* for an entry with the specified key. If such an entry is found, |
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* <tt>true</tt> is returned. If the iteration terminates without |
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* finding such an entry, <tt>false</tt> is returned. Note that this |
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* implementation requires linear time in the size of the map; many |
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* implementations will override this method. |
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* |
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* This implementation iterates over <tt>entrySet()</tt> searching for an |
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* entry with the specified key. If such an entry is found, <tt>true</tt> |
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* is returned. If the iteration terminates without finding such an |
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* entry, <tt>false</tt> is returned. Note that this implementation |
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* requires linear time in the size of the map; many implementations will |
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* override this method. |
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* |
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* @param key key whose presence in this map is to be tested. |
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* @return <tt>true</tt> if this map contains a mapping for the specified |
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* key. |
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* |
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* @throws NullPointerException if the key is <tt>null</tt> and this map |
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* does not permit <tt>null</tt> keys. |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public boolean containsKey(Object key) { |
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Iterator<Map.Entry<K,V>> i = entrySet().iterator(); |
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} |
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|
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/** |
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* Returns the value to which this map maps the specified key. Returns |
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* <tt>null</tt> if the map contains no mapping for this key. A return |
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* value of <tt>null</tt> does not <i>necessarily</i> indicate that the |
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* map contains no mapping for the key; it's also possible that the map |
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* explicitly maps the key to <tt>null</tt>. The containsKey operation |
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* may be used to distinguish these two cases. <p> |
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* |
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* This implementation iterates over <tt>entrySet()</tt> searching for an |
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* entry with the specified key. If such an entry is found, the entry's |
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* value is returned. If the iteration terminates without finding such an |
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* entry, <tt>null</tt> is returned. Note that this implementation |
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* requires linear time in the size of the map; many implementations will |
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* override this method. |
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* |
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* @param key key whose associated value is to be returned. |
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* @return the value to which this map maps the specified key. |
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* |
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* @throws NullPointerException if the key is <tt>null</tt> and this map |
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* does not permit <tt>null</tt> keys. |
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* |
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* @see #containsKey(Object) |
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* {@inheritDoc} |
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* |
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* <p>This implementation iterates over <tt>entrySet()</tt> searching |
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* for an entry with the specified key. If such an entry is found, |
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* the entry's value is returned. If the iteration terminates without |
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* finding such an entry, <tt>null</tt> is returned. Note that this |
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* implementation requires linear time in the size of the map; many |
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* implementations will override this method. |
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* |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public V get(Object key) { |
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Iterator<Entry<K,V>> i = entrySet().iterator(); |
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// Modification Operations |
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|
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/** |
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* Associates the specified value with the specified key in this map |
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* (optional operation). If the map previously contained a mapping for |
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* this key, the old value is replaced.<p> |
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* {@inheritDoc} |
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* |
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* This implementation always throws an |
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* <p>This implementation always throws an |
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* <tt>UnsupportedOperationException</tt>. |
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* |
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* @param key key with which the specified value is to be associated. |
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* @param value value to be associated with the specified key. |
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* |
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* @return previous value associated with specified key, or <tt>null</tt> |
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* if there was no mapping for key. (A <tt>null</tt> return can |
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* also indicate that the map previously associated <tt>null</tt> |
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* with the specified key, if the implementation supports |
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* <tt>null</tt> values.) |
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* |
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* @throws UnsupportedOperationException if the <tt>put</tt> operation is |
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* not supported by this map. |
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< |
* |
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* @throws ClassCastException if the class of the specified key or value |
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* prevents it from being stored in this map. |
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* |
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* @throws IllegalArgumentException if some aspect of this key or value * |
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* prevents it from being stored in this map. |
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* |
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* @throws NullPointerException if this map does not permit <tt>null</tt> |
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* keys or values, and the specified key or value is |
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* <tt>null</tt>. |
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* @throws UnsupportedOperationException {@inheritDoc} |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
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* @throws IllegalArgumentException {@inheritDoc} |
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*/ |
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public V put(K key, V value) { |
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throw new UnsupportedOperationException(); |
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} |
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|
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/** |
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* Removes the mapping for this key from this map if present (optional |
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* operation). <p> |
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* {@inheritDoc} |
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* |
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* This implementation iterates over <tt>entrySet()</tt> searching for an |
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> |
* <p>This implementation iterates over <tt>entrySet()</tt> searching for an |
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* entry with the specified key. If such an entry is found, its value is |
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* obtained with its <tt>getValue</tt> operation, the entry is removed |
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* from the Collection (and the backing map) with the iterator's |
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* from the collection (and the backing map) with the iterator's |
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* <tt>remove</tt> operation, and the saved value is returned. If the |
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* iteration terminates without finding such an entry, <tt>null</tt> is |
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* returned. Note that this implementation requires linear time in the |
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* size of the map; many implementations will override this method.<p> |
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> |
* size of the map; many implementations will override this method. |
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* |
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< |
* Note that this implementation throws an |
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* <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> iterator |
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* does not support the <tt>remove</tt> method and this map contains a |
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* mapping for the specified key. |
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* |
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* @param key key whose mapping is to be removed from the map. |
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* @return previous value associated with specified key, or <tt>null</tt> |
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* if there was no entry for key. (A <tt>null</tt> return can |
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< |
* also indicate that the map previously associated <tt>null</tt> |
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* with the specified key, if the implementation supports |
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* <tt>null</tt> values.) |
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* @throws UnsupportedOperationException if the <tt>remove</tt> operation |
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* is not supported by this map. |
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> |
* <p>Note that this implementation throws an |
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* <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> |
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* iterator does not support the <tt>remove</tt> method and this map |
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* contains a mapping for the specified key. |
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* |
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> |
* @throws UnsupportedOperationException {@inheritDoc} |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
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*/ |
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public V remove(Object key) { |
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Iterator<Entry<K,V>> i = entrySet().iterator(); |
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// Bulk Operations |
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|
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/** |
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* Copies all of the mappings from the specified map to this map |
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* (optional operation). These mappings will replace any mappings that |
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* this map had for any of the keys currently in the specified map.<p> |
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> |
* {@inheritDoc} |
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* |
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< |
* This implementation iterates over the specified map's |
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> |
* <p>This implementation iterates over the specified map's |
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* <tt>entrySet()</tt> collection, and calls this map's <tt>put</tt> |
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* operation once for each entry returned by the iteration.<p> |
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> |
* operation once for each entry returned by the iteration. |
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* |
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< |
* Note that this implementation throws an |
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> |
* <p>Note that this implementation throws an |
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* <tt>UnsupportedOperationException</tt> if this map does not support |
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* the <tt>put</tt> operation and the specified map is nonempty. |
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* |
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< |
* @param t mappings to be stored in this map. |
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< |
* |
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< |
* @throws UnsupportedOperationException if the <tt>putAll</tt> operation |
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* is not supported by this map. |
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< |
* |
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< |
* @throws ClassCastException if the class of a key or value in the |
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< |
* specified map prevents it from being stored in this map. |
| 274 |
< |
* |
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< |
* @throws IllegalArgumentException if some aspect of a key or value in |
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< |
* the specified map prevents it from being stored in this map. |
| 309 |
< |
* @throws NullPointerException if the specified map is <tt>null</tt>, or if |
| 310 |
< |
* this map does not permit <tt>null</tt> keys or values, and the |
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< |
* specified map contains <tt>null</tt> keys or values. |
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< |
*/ |
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< |
public void putAll(Map<? extends K, ? extends V> t) { |
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< |
Iterator<? extends Entry<? extends K, ? extends V>> i = t.entrySet().iterator(); |
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< |
while (i.hasNext()) { |
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< |
Entry<? extends K, ? extends V> e = i.next(); |
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< |
put(e.getKey(), e.getValue()); |
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< |
} |
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> |
* @throws UnsupportedOperationException {@inheritDoc} |
| 268 |
> |
* @throws ClassCastException {@inheritDoc} |
| 269 |
> |
* @throws NullPointerException {@inheritDoc} |
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> |
* @throws IllegalArgumentException {@inheritDoc} |
| 271 |
> |
*/ |
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> |
public void putAll(Map<? extends K, ? extends V> m) { |
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> |
for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) |
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> |
put(e.getKey(), e.getValue()); |
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} |
| 276 |
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|
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|
/** |
| 278 |
< |
* Removes all mappings from this map (optional operation). <p> |
| 278 |
> |
* {@inheritDoc} |
| 279 |
|
* |
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< |
* This implementation calls <tt>entrySet().clear()</tt>. |
| 280 |
> |
* <p>This implementation calls <tt>entrySet().clear()</tt>. |
| 281 |
|
* |
| 282 |
< |
* Note that this implementation throws an |
| 282 |
> |
* <p>Note that this implementation throws an |
| 283 |
|
* <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> |
| 284 |
|
* does not support the <tt>clear</tt> operation. |
| 285 |
|
* |
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< |
* @throws UnsupportedOperationException clear is not supported |
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< |
* by this map. |
| 286 |
> |
* @throws UnsupportedOperationException {@inheritDoc} |
| 287 |
|
*/ |
| 288 |
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public void clear() { |
| 289 |
|
entrySet().clear(); |
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transient volatile Collection<V> values = null; |
| 302 |
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|
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/** |
| 304 |
< |
* Returns a Set view of the keys contained in this map. The Set is |
| 305 |
< |
* backed by the map, so changes to the map are reflected in the Set, |
| 306 |
< |
* and vice-versa. (If the map is modified while an iteration over |
| 307 |
< |
* the Set is in progress, the results of the iteration are undefined.) |
| 308 |
< |
* The Set supports element removal, which removes the corresponding entry |
| 309 |
< |
* from the map, via the Iterator.remove, Set.remove, removeAll |
| 310 |
< |
* retainAll, and clear operations. It does not support the add or |
| 311 |
< |
* addAll operations.<p> |
| 357 |
< |
* |
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< |
* This implementation returns a Set that subclasses |
| 359 |
< |
* AbstractSet. The subclass's iterator method returns a "wrapper |
| 360 |
< |
* object" over this map's entrySet() iterator. The size method delegates |
| 361 |
< |
* to this map's size method and the contains method delegates to this |
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< |
* map's containsKey method.<p> |
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> |
* {@inheritDoc} |
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> |
* |
| 306 |
> |
* <p>This implementation returns a set that subclasses {@link AbstractSet}. |
| 307 |
> |
* The subclass's iterator method returns a "wrapper object" over this |
| 308 |
> |
* map's <tt>entrySet()</tt> iterator. The <tt>size</tt> method |
| 309 |
> |
* delegates to this map's <tt>size</tt> method and the |
| 310 |
> |
* <tt>contains</tt> method delegates to this map's |
| 311 |
> |
* <tt>containsKey</tt> method. |
| 312 |
|
* |
| 313 |
< |
* The Set is created the first time this method is called, |
| 313 |
> |
* <p>The set is created the first time this method is called, |
| 314 |
|
* and returned in response to all subsequent calls. No synchronization |
| 315 |
|
* is performed, so there is a slight chance that multiple calls to this |
| 316 |
< |
* method will not all return the same Set. |
| 368 |
< |
* |
| 369 |
< |
* @return a Set view of the keys contained in this map. |
| 316 |
> |
* method will not all return the same set. |
| 317 |
|
*/ |
| 318 |
|
public Set<K> keySet() { |
| 319 |
|
if (keySet == null) { |
| 349 |
|
} |
| 350 |
|
|
| 351 |
|
/** |
| 352 |
< |
* Returns a collection view of the values contained in this map. The |
| 353 |
< |
* collection is backed by the map, so changes to the map are reflected in |
| 354 |
< |
* the collection, and vice-versa. (If the map is modified while an |
| 355 |
< |
* iteration over the collection is in progress, the results of the |
| 356 |
< |
* iteration are undefined.) The collection supports element removal, |
| 357 |
< |
* which removes the corresponding entry from the map, via the |
| 358 |
< |
* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>, |
| 359 |
< |
* <tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt> operations. |
| 413 |
< |
* It does not support the <tt>add</tt> or <tt>addAll</tt> operations.<p> |
| 414 |
< |
* |
| 415 |
< |
* This implementation returns a collection that subclasses abstract |
| 416 |
< |
* collection. The subclass's iterator method returns a "wrapper object" |
| 417 |
< |
* over this map's <tt>entrySet()</tt> iterator. The size method |
| 418 |
< |
* delegates to this map's size method and the contains method delegates |
| 419 |
< |
* to this map's containsValue method.<p> |
| 352 |
> |
* {@inheritDoc} |
| 353 |
> |
* |
| 354 |
> |
* <p>This implementation returns a collection that subclasses {@link |
| 355 |
> |
* AbstractCollection}. The subclass's iterator method returns a |
| 356 |
> |
* "wrapper object" over this map's <tt>entrySet()</tt> iterator. |
| 357 |
> |
* The <tt>size</tt> method delegates to this map's <tt>size</tt> |
| 358 |
> |
* method and the <tt>contains</tt> method delegates to this map's |
| 359 |
> |
* <tt>containsValue</tt> method. |
| 360 |
|
* |
| 361 |
< |
* The collection is created the first time this method is called, and |
| 361 |
> |
* <p>The collection is created the first time this method is called, and |
| 362 |
|
* returned in response to all subsequent calls. No synchronization is |
| 363 |
|
* performed, so there is a slight chance that multiple calls to this |
| 364 |
< |
* method will not all return the same Collection. |
| 425 |
< |
* |
| 426 |
< |
* @return a collection view of the values contained in this map. |
| 364 |
> |
* method will not all return the same collection. |
| 365 |
|
*/ |
| 366 |
|
public Collection<V> values() { |
| 367 |
|
if (values == null) { |
| 396 |
|
return values; |
| 397 |
|
} |
| 398 |
|
|
| 461 |
– |
/** |
| 462 |
– |
* Returns a set view of the mappings contained in this map. Each element |
| 463 |
– |
* in this set is a Map.Entry. The set is backed by the map, so changes |
| 464 |
– |
* to the map are reflected in the set, and vice-versa. (If the map is |
| 465 |
– |
* modified while an iteration over the set is in progress, the results of |
| 466 |
– |
* the iteration are undefined.) The set supports element removal, which |
| 467 |
– |
* removes the corresponding entry from the map, via the |
| 468 |
– |
* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, <tt>removeAll</tt>, |
| 469 |
– |
* <tt>retainAll</tt> and <tt>clear</tt> operations. It does not support |
| 470 |
– |
* the <tt>add</tt> or <tt>addAll</tt> operations. |
| 471 |
– |
* |
| 472 |
– |
* @return a set view of the mappings contained in this map. |
| 473 |
– |
*/ |
| 399 |
|
public abstract Set<Entry<K,V>> entrySet(); |
| 400 |
|
|
| 401 |
|
|
| 404 |
|
/** |
| 405 |
|
* Compares the specified object with this map for equality. Returns |
| 406 |
|
* <tt>true</tt> if the given object is also a map and the two maps |
| 407 |
< |
* represent the same mappings. More formally, two maps <tt>t1</tt> and |
| 408 |
< |
* <tt>t2</tt> represent the same mappings if |
| 409 |
< |
* <tt>t1.keySet().equals(t2.keySet())</tt> and for every key <tt>k</tt> |
| 485 |
< |
* in <tt>t1.keySet()</tt>, <tt> (t1.get(k)==null ? t2.get(k)==null : |
| 486 |
< |
* t1.get(k).equals(t2.get(k))) </tt>. This ensures that the |
| 407 |
> |
* represent the same mappings. More formally, two maps <tt>m1</tt> and |
| 408 |
> |
* <tt>m2</tt> represent the same mappings if |
| 409 |
> |
* <tt>m1.entrySet().equals(m2.entrySet())</tt>. This ensures that the |
| 410 |
|
* <tt>equals</tt> method works properly across different implementations |
| 411 |
< |
* of the map interface.<p> |
| 411 |
> |
* of the <tt>Map</tt> interface. |
| 412 |
|
* |
| 413 |
< |
* This implementation first checks if the specified object is this map; |
| 413 |
> |
* <p>This implementation first checks if the specified object is this map; |
| 414 |
|
* if so it returns <tt>true</tt>. Then, it checks if the specified |
| 415 |
< |
* object is a map whose size is identical to the size of this set; if |
| 415 |
> |
* object is a map whose size is identical to the size of this map; if |
| 416 |
|
* not, it returns <tt>false</tt>. If so, it iterates over this map's |
| 417 |
|
* <tt>entrySet</tt> collection, and checks that the specified map |
| 418 |
|
* contains each mapping that this map contains. If the specified map |
| 419 |
|
* fails to contain such a mapping, <tt>false</tt> is returned. If the |
| 420 |
|
* iteration completes, <tt>true</tt> is returned. |
| 421 |
|
* |
| 422 |
< |
* @param o object to be compared for equality with this map. |
| 423 |
< |
* @return <tt>true</tt> if the specified object is equal to this map. |
| 422 |
> |
* @param o object to be compared for equality with this map |
| 423 |
> |
* @return <tt>true</tt> if the specified object is equal to this map |
| 424 |
|
*/ |
| 425 |
|
public boolean equals(Object o) { |
| 426 |
|
if (o == this) |
| 428 |
|
|
| 429 |
|
if (!(o instanceof Map)) |
| 430 |
|
return false; |
| 431 |
< |
Map<K,V> t = (Map<K,V>) o; |
| 432 |
< |
if (t.size() != size()) |
| 431 |
> |
Map<K,V> m = (Map<K,V>) o; |
| 432 |
> |
if (m.size() != size()) |
| 433 |
|
return false; |
| 434 |
|
|
| 435 |
|
try { |
| 439 |
|
K key = e.getKey(); |
| 440 |
|
V value = e.getValue(); |
| 441 |
|
if (value == null) { |
| 442 |
< |
if (!(t.get(key)==null && t.containsKey(key))) |
| 442 |
> |
if (!(m.get(key)==null && m.containsKey(key))) |
| 443 |
|
return false; |
| 444 |
|
} else { |
| 445 |
< |
if (!value.equals(t.get(key))) |
| 445 |
> |
if (!value.equals(m.get(key))) |
| 446 |
|
return false; |
| 447 |
|
} |
| 448 |
|
} |
| 449 |
< |
} catch(ClassCastException unused) { |
| 449 |
> |
} catch (ClassCastException unused) { |
| 450 |
|
return false; |
| 451 |
< |
} catch(NullPointerException unused) { |
| 451 |
> |
} catch (NullPointerException unused) { |
| 452 |
|
return false; |
| 453 |
|
} |
| 454 |
|
|
| 458 |
|
/** |
| 459 |
|
* Returns the hash code value for this map. The hash code of a map is |
| 460 |
|
* defined to be the sum of the hash codes of each entry in the map's |
| 461 |
< |
* <tt>entrySet()</tt> view. This ensures that <tt>t1.equals(t2)</tt> |
| 462 |
< |
* implies that <tt>t1.hashCode()==t2.hashCode()</tt> for any two maps |
| 463 |
< |
* <tt>t1</tt> and <tt>t2</tt>, as required by the general contract of |
| 464 |
< |
* Object.hashCode.<p> |
| 465 |
< |
* |
| 466 |
< |
* This implementation iterates over <tt>entrySet()</tt>, calling |
| 467 |
< |
* <tt>hashCode</tt> on each element (entry) in the Collection, and adding |
| 468 |
< |
* up the results. |
| 461 |
> |
* <tt>entrySet()</tt> view. This ensures that <tt>m1.equals(m2)</tt> |
| 462 |
> |
* implies that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps |
| 463 |
> |
* <tt>m1</tt> and <tt>m2</tt>, as required by the general contract of |
| 464 |
> |
* {@link Object#hashCode}. |
| 465 |
> |
* |
| 466 |
> |
* <p>This implementation iterates over <tt>entrySet()</tt>, calling |
| 467 |
> |
* {@link Map.Entry#hashCode hashCode()} on each element (entry) in the |
| 468 |
> |
* set, and adding up the results. |
| 469 |
|
* |
| 470 |
< |
* @return the hash code value for this map. |
| 470 |
> |
* @return the hash code value for this map |
| 471 |
|
* @see Map.Entry#hashCode() |
| 549 |
– |
* @see Object#hashCode() |
| 472 |
|
* @see Object#equals(Object) |
| 473 |
|
* @see Set#equals(Object) |
| 474 |
|
*/ |
| 488 |
|
* <tt>", "</tt> (comma and space). Each key-value mapping is rendered as |
| 489 |
|
* the key followed by an equals sign (<tt>"="</tt>) followed by the |
| 490 |
|
* associated value. Keys and values are converted to strings as by |
| 491 |
< |
* <tt>String.valueOf(Object)</tt>.<p> |
| 570 |
< |
* |
| 571 |
< |
* This implementation creates an empty string buffer, appends a left |
| 572 |
< |
* brace, and iterates over the map's <tt>entrySet</tt> view, appending |
| 573 |
< |
* the string representation of each <tt>map.entry</tt> in turn. After |
| 574 |
< |
* appending each entry except the last, the string <tt>", "</tt> is |
| 575 |
< |
* appended. Finally a right brace is appended. A string is obtained |
| 576 |
< |
* from the stringbuffer, and returned. |
| 491 |
> |
* {@link String#valueOf(Object)}. |
| 492 |
|
* |
| 493 |
< |
* @return a String representation of this map. |
| 493 |
> |
* @return a string representation of this map |
| 494 |
|
*/ |
| 495 |
|
public String toString() { |
| 581 |
– |
StringBuffer buf = new StringBuffer(); |
| 582 |
– |
buf.append("{"); |
| 583 |
– |
|
| 496 |
|
Iterator<Entry<K,V>> i = entrySet().iterator(); |
| 497 |
< |
boolean hasNext = i.hasNext(); |
| 498 |
< |
while (hasNext) { |
| 497 |
> |
if (! i.hasNext()) |
| 498 |
> |
return "{}"; |
| 499 |
> |
|
| 500 |
> |
StringBuilder sb = new StringBuilder(); |
| 501 |
> |
sb.append('{'); |
| 502 |
> |
for (;;) { |
| 503 |
|
Entry<K,V> e = i.next(); |
| 504 |
|
K key = e.getKey(); |
| 505 |
< |
V value = e.getValue(); |
| 506 |
< |
if (key == this) |
| 507 |
< |
buf.append("(this Map)"); |
| 508 |
< |
else |
| 509 |
< |
buf.append(key); |
| 510 |
< |
buf.append("="); |
| 511 |
< |
if (value == this) |
| 512 |
< |
buf.append("(this Map)"); |
| 597 |
< |
else |
| 598 |
< |
buf.append(value); |
| 599 |
< |
hasNext = i.hasNext(); |
| 600 |
< |
if (hasNext) |
| 601 |
< |
buf.append(", "); |
| 602 |
< |
} |
| 603 |
< |
|
| 604 |
< |
buf.append("}"); |
| 605 |
< |
return buf.toString(); |
| 505 |
> |
V value = e.getValue(); |
| 506 |
> |
sb.append(key == this ? "(this Map)" : key); |
| 507 |
> |
sb.append('='); |
| 508 |
> |
sb.append(value == this ? "(this Map)" : value); |
| 509 |
> |
if (! i.hasNext()) |
| 510 |
> |
return sb.append('}').toString(); |
| 511 |
> |
sb.append(", "); |
| 512 |
> |
} |
| 513 |
|
} |
| 514 |
< |
|
| 514 |
> |
|
| 515 |
|
/** |
| 516 |
|
* Returns a shallow copy of this <tt>AbstractMap</tt> instance: the keys |
| 517 |
|
* and values themselves are not cloned. |
| 518 |
|
* |
| 519 |
< |
* @return a shallow copy of this map. |
| 519 |
> |
* @return a shallow copy of this map |
| 520 |
|
*/ |
| 521 |
|
protected Object clone() throws CloneNotSupportedException { |
| 522 |
|
AbstractMap<K,V> result = (AbstractMap<K,V>)super.clone(); |
| 530 |
|
* Test for equality, checking for nulls. |
| 531 |
|
*/ |
| 532 |
|
private static boolean eq(Object o1, Object o2) { |
| 533 |
< |
return (o1 == null ? o2 == null : o1.equals(o2)); |
| 533 |
> |
return o1 == null ? o2 == null : o1.equals(o2); |
| 534 |
|
} |
| 535 |
|
|
| 536 |
|
// Implementation Note: SimpleEntry and SimpleImmutableEntry |
| 547 |
|
* facilitates the process of building custom map |
| 548 |
|
* implementations. For example, it may be convenient to return |
| 549 |
|
* arrays of <tt>SimpleEntry</tt> instances in method |
| 550 |
< |
* <tt>Map.entrySet().toArray</tt> |
| 550 |
> |
* <tt>Map.entrySet().toArray</tt>. |
| 551 |
> |
* |
| 552 |
> |
* @since 1.6 |
| 553 |
|
*/ |
| 554 |
< |
public static class SimpleEntry<K,V> implements Entry<K,V> { |
| 554 |
> |
public static class SimpleEntry<K,V> |
| 555 |
> |
implements Entry<K,V>, java.io.Serializable |
| 556 |
> |
{ |
| 557 |
> |
private static final long serialVersionUID = -8499721149061103585L; |
| 558 |
> |
|
| 559 |
|
private final K key; |
| 560 |
|
private V value; |
| 561 |
|
|
| 575 |
|
* Creates an entry representing the same mapping as the |
| 576 |
|
* specified entry. |
| 577 |
|
* |
| 578 |
< |
* @param entry the entry to copy. |
| 578 |
> |
* @param entry the entry to copy |
| 579 |
|
*/ |
| 580 |
|
public SimpleEntry(Entry<? extends K, ? extends V> entry) { |
| 581 |
|
this.key = entry.getKey(); |
| 585 |
|
/** |
| 586 |
|
* Returns the key corresponding to this entry. |
| 587 |
|
* |
| 588 |
< |
* @return the key corresponding to this entry. |
| 588 |
> |
* @return the key corresponding to this entry |
| 589 |
|
*/ |
| 590 |
|
public K getKey() { |
| 591 |
|
return key; |
| 594 |
|
/** |
| 595 |
|
* Returns the value corresponding to this entry. |
| 596 |
|
* |
| 597 |
< |
* @return the value corresponding to this entry. |
| 597 |
> |
* @return the value corresponding to this entry |
| 598 |
|
*/ |
| 599 |
|
public V getValue() { |
| 600 |
|
return value; |
| 604 |
|
* Replaces the value corresponding to this entry with the specified |
| 605 |
|
* value. |
| 606 |
|
* |
| 607 |
< |
* @param value new value to be stored in this entry. |
| 608 |
< |
* @return old value corresponding to the entry. |
| 607 |
> |
* @param value new value to be stored in this entry |
| 608 |
> |
* @return the old value corresponding to the entry |
| 609 |
|
*/ |
| 610 |
|
public V setValue(V value) { |
| 611 |
|
V oldValue = this.value; |
| 613 |
|
return oldValue; |
| 614 |
|
} |
| 615 |
|
|
| 616 |
+ |
/** |
| 617 |
+ |
* Compares the specified object with this entry for equality. |
| 618 |
+ |
* Returns {@code true} if the given object is also a map entry and |
| 619 |
+ |
* the two entries represent the same mapping. More formally, two |
| 620 |
+ |
* entries {@code e1} and {@code e2} represent the same mapping |
| 621 |
+ |
* if<pre> |
| 622 |
+ |
* (e1.getKey()==null ? |
| 623 |
+ |
* e2.getKey()==null : |
| 624 |
+ |
* e1.getKey().equals(e2.getKey())) |
| 625 |
+ |
* && |
| 626 |
+ |
* (e1.getValue()==null ? |
| 627 |
+ |
* e2.getValue()==null : |
| 628 |
+ |
* e1.getValue().equals(e2.getValue()))</pre> |
| 629 |
+ |
* This ensures that the {@code equals} method works properly across |
| 630 |
+ |
* different implementations of the {@code Map.Entry} interface. |
| 631 |
+ |
* |
| 632 |
+ |
* @param o object to be compared for equality with this map entry |
| 633 |
+ |
* @return {@code true} if the specified object is equal to this map |
| 634 |
+ |
* entry |
| 635 |
+ |
* @see #hashCode |
| 636 |
+ |
*/ |
| 637 |
|
public boolean equals(Object o) { |
| 638 |
|
if (!(o instanceof Map.Entry)) |
| 639 |
|
return false; |
| 641 |
|
return eq(key, e.getKey()) && eq(value, e.getValue()); |
| 642 |
|
} |
| 643 |
|
|
| 644 |
+ |
/** |
| 645 |
+ |
* Returns the hash code value for this map entry. The hash code |
| 646 |
+ |
* of a map entry {@code e} is defined to be: <pre> |
| 647 |
+ |
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ |
| 648 |
+ |
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> |
| 649 |
+ |
* This ensures that {@code e1.equals(e2)} implies that |
| 650 |
+ |
* {@code e1.hashCode()==e2.hashCode()} for any two Entries |
| 651 |
+ |
* {@code e1} and {@code e2}, as required by the general |
| 652 |
+ |
* contract of {@link Object#hashCode}. |
| 653 |
+ |
* |
| 654 |
+ |
* @return the hash code value for this map entry |
| 655 |
+ |
* @see #equals |
| 656 |
+ |
*/ |
| 657 |
|
public int hashCode() { |
| 658 |
< |
return ((key == null) ? 0 : key.hashCode()) ^ |
| 659 |
< |
((value == null) ? 0 : value.hashCode()); |
| 658 |
> |
return (key == null ? 0 : key.hashCode()) ^ |
| 659 |
> |
(value == null ? 0 : value.hashCode()); |
| 660 |
|
} |
| 661 |
|
|
| 662 |
|
/** |
| 665 |
|
* entry's key followed by the equals character ("<tt>=</tt>") |
| 666 |
|
* followed by the string representation of this entry's value. |
| 667 |
|
* |
| 668 |
< |
* @return a String representation of this map entry. |
| 668 |
> |
* @return a String representation of this map entry |
| 669 |
|
*/ |
| 670 |
|
public String toString() { |
| 671 |
|
return key + "=" + value; |
| 674 |
|
} |
| 675 |
|
|
| 676 |
|
/** |
| 677 |
< |
* An Entry maintaining an immutable key and value, This class |
| 677 |
> |
* An Entry maintaining an immutable key and value. This class |
| 678 |
|
* does not support method <tt>setValue</tt>. This class may be |
| 679 |
|
* convenient in methods that return thread-safe snapshots of |
| 680 |
|
* key-value mappings. |
| 681 |
+ |
* |
| 682 |
+ |
* @since 1.6 |
| 683 |
|
*/ |
| 684 |
< |
public static class SimpleImmutableEntry<K,V> implements Entry<K,V> { |
| 684 |
> |
public static class SimpleImmutableEntry<K,V> |
| 685 |
> |
implements Entry<K,V>, java.io.Serializable |
| 686 |
> |
{ |
| 687 |
> |
private static final long serialVersionUID = 7138329143949025153L; |
| 688 |
> |
|
| 689 |
|
private final K key; |
| 690 |
|
private final V value; |
| 691 |
|
|
| 705 |
|
* Creates an entry representing the same mapping as the |
| 706 |
|
* specified entry. |
| 707 |
|
* |
| 708 |
< |
* @param entry the entry to copy. |
| 708 |
> |
* @param entry the entry to copy |
| 709 |
|
*/ |
| 710 |
|
public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) { |
| 711 |
|
this.key = entry.getKey(); |
| 715 |
|
/** |
| 716 |
|
* Returns the key corresponding to this entry. |
| 717 |
|
* |
| 718 |
< |
* @return the key corresponding to this entry. |
| 718 |
> |
* @return the key corresponding to this entry |
| 719 |
|
*/ |
| 720 |
|
public K getKey() { |
| 721 |
|
return key; |
| 724 |
|
/** |
| 725 |
|
* Returns the value corresponding to this entry. |
| 726 |
|
* |
| 727 |
< |
* @return the value corresponding to this entry. |
| 727 |
> |
* @return the value corresponding to this entry |
| 728 |
|
*/ |
| 729 |
|
public V getValue() { |
| 730 |
|
return value; |
| 736 |
|
* <tt>UnsupportedOperationException</tt>, as this class implements |
| 737 |
|
* an <i>immutable</i> map entry. |
| 738 |
|
* |
| 739 |
< |
* @param value new value to be stored in this entry. |
| 739 |
> |
* @param value new value to be stored in this entry |
| 740 |
|
* @return (Does not return) |
| 741 |
|
* @throws UnsupportedOperationException always |
| 742 |
|
*/ |
| 744 |
|
throw new UnsupportedOperationException(); |
| 745 |
|
} |
| 746 |
|
|
| 747 |
+ |
/** |
| 748 |
+ |
* Compares the specified object with this entry for equality. |
| 749 |
+ |
* Returns {@code true} if the given object is also a map entry and |
| 750 |
+ |
* the two entries represent the same mapping. More formally, two |
| 751 |
+ |
* entries {@code e1} and {@code e2} represent the same mapping |
| 752 |
+ |
* if<pre> |
| 753 |
+ |
* (e1.getKey()==null ? |
| 754 |
+ |
* e2.getKey()==null : |
| 755 |
+ |
* e1.getKey().equals(e2.getKey())) |
| 756 |
+ |
* && |
| 757 |
+ |
* (e1.getValue()==null ? |
| 758 |
+ |
* e2.getValue()==null : |
| 759 |
+ |
* e1.getValue().equals(e2.getValue()))</pre> |
| 760 |
+ |
* This ensures that the {@code equals} method works properly across |
| 761 |
+ |
* different implementations of the {@code Map.Entry} interface. |
| 762 |
+ |
* |
| 763 |
+ |
* @param o object to be compared for equality with this map entry |
| 764 |
+ |
* @return {@code true} if the specified object is equal to this map |
| 765 |
+ |
* entry |
| 766 |
+ |
* @see #hashCode |
| 767 |
+ |
*/ |
| 768 |
|
public boolean equals(Object o) { |
| 769 |
|
if (!(o instanceof Map.Entry)) |
| 770 |
|
return false; |
| 772 |
|
return eq(key, e.getKey()) && eq(value, e.getValue()); |
| 773 |
|
} |
| 774 |
|
|
| 775 |
+ |
/** |
| 776 |
+ |
* Returns the hash code value for this map entry. The hash code |
| 777 |
+ |
* of a map entry {@code e} is defined to be: <pre> |
| 778 |
+ |
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ |
| 779 |
+ |
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> |
| 780 |
+ |
* This ensures that {@code e1.equals(e2)} implies that |
| 781 |
+ |
* {@code e1.hashCode()==e2.hashCode()} for any two Entries |
| 782 |
+ |
* {@code e1} and {@code e2}, as required by the general |
| 783 |
+ |
* contract of {@link Object#hashCode}. |
| 784 |
+ |
* |
| 785 |
+ |
* @return the hash code value for this map entry |
| 786 |
+ |
* @see #equals |
| 787 |
+ |
*/ |
| 788 |
|
public int hashCode() { |
| 789 |
< |
return ((key == null) ? 0 : key.hashCode()) ^ |
| 790 |
< |
((value == null) ? 0 : value.hashCode()); |
| 789 |
> |
return (key == null ? 0 : key.hashCode()) ^ |
| 790 |
> |
(value == null ? 0 : value.hashCode()); |
| 791 |
|
} |
| 792 |
|
|
| 793 |
|
/** |
| 796 |
|
* entry's key followed by the equals character ("<tt>=</tt>") |
| 797 |
|
* followed by the string representation of this entry's value. |
| 798 |
|
* |
| 799 |
< |
* @return a String representation of this map entry. |
| 799 |
> |
* @return a String representation of this map entry |
| 800 |
|
*/ |
| 801 |
|
public String toString() { |
| 802 |
|
return key + "=" + value; |
