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/* |
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* %W% %E% |
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* Copyright 1997-2007 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 2005 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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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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// 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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* {@inheritDoc} |
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* |
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* This implementation returns <tt>entrySet().size()</tt>. |
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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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* 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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* 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 <tt>Map</tt>.<p> |
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* |
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* This implementation iterates over <tt>entrySet()</tt> 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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* {@inheritDoc} |
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* |
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* @param value value whose presence in this map is to be tested. |
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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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* @return <tt>true</tt> if this map maps one or more keys to this value. |
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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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* 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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* @throws NullPointerException if <tt>key</tt> is <tt>null</tt> |
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* and this map does not permit <tt>null</tt> keys. |
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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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* @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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* {@inheritDoc} |
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* |
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* @throws NullPointerException if <tt>key</tt> is <tt>null</tt> |
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* and this map does not permit <tt>null</tt> keys. |
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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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* @see #containsKey(Object) |
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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 the 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 |
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* is not supported by this map. |
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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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* @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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* @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 <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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* 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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* <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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* <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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* 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 the 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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* @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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* @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. |
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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. |
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* @throws NullPointerException if the specified map is <tt>null</tt>, or if |
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* 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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* @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 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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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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} |
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|
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/** |
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* Removes all mappings from this map (optional operation). <p> |
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* {@inheritDoc} |
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* |
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* This implementation calls <tt>entrySet().clear()</tt>. |
280 |
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* <p>This implementation calls <tt>entrySet().clear()</tt>. |
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* |
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< |
* Note that this implementation throws an |
282 |
> |
* <p>Note that this implementation throws an |
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* <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> |
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* does not support the <tt>clear</tt> operation. |
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* |
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* @throws UnsupportedOperationException if the <tt>clear</tt> operation |
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* is not supported by this map. |
286 |
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* @throws UnsupportedOperationException {@inheritDoc} |
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*/ |
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public void clear() { |
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entrySet().clear(); |
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transient volatile Collection<V> values = null; |
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|
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/** |
304 |
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* Returns a {@link Set} view of the keys contained in this map. |
346 |
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* The set is backed by the map, so changes to the map are |
347 |
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* reflected in the set, and vice-versa. If the map is modified |
348 |
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* while an iteration over the set is in progress (except through |
349 |
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* the iterator's own <tt>remove</tt> operation), the results of |
350 |
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* the iteration are undefined. The set supports element removal, |
351 |
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* which removes the corresponding mapping from the map, via the |
352 |
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* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
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* <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt> |
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* operations. It does not support the add or <tt>addAll</tt> |
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* operations. |
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* {@inheritDoc} |
305 |
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* |
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* <p>This implementation returns a set that subclasses {@link AbstractSet}. |
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* The subclass's iterator method returns a "wrapper object" over this |
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return AbstractMap.this.size(); |
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} |
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|
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+ |
public boolean isEmpty() { |
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+ |
return AbstractMap.this.isEmpty(); |
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+ |
} |
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+ |
|
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+ |
public void clear() { |
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+ |
AbstractMap.this.clear(); |
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+ |
} |
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+ |
|
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public boolean contains(Object k) { |
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return AbstractMap.this.containsKey(k); |
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} |
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} |
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|
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/** |
360 |
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* Returns a {@link Collection} view of the values contained in this map. |
404 |
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* The collection is backed by the map, so changes to the map are |
405 |
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* reflected in the collection, and vice-versa. If the map is |
406 |
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* modified while an iteration over the collection is in progress |
407 |
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* (except through the iterator's own <tt>remove</tt> operation), |
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* the results of the iteration are undefined. The collection |
409 |
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* supports element removal, which removes the corresponding |
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* mapping from the map, via the <tt>Iterator.remove</tt>, |
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* <tt>Collection.remove</tt>, <tt>removeAll</tt>, |
412 |
< |
* <tt>retainAll</tt> and <tt>clear</tt> operations. It does not |
413 |
< |
* support the add or <tt>addAll</tt> operations. |
360 |
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* {@inheritDoc} |
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* |
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* <p>This implementation returns a collection that subclasses {@link |
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|
* AbstractCollection}. The subclass's iterator method returns a |
370 |
|
* returned in response to all subsequent calls. No synchronization is |
371 |
|
* performed, so there is a slight chance that multiple calls to this |
372 |
|
* method will not all return the same collection. |
426 |
– |
* |
427 |
– |
* @return a collection view of the values contained in this map. |
373 |
|
*/ |
374 |
|
public Collection<V> values() { |
375 |
|
if (values == null) { |
396 |
|
return AbstractMap.this.size(); |
397 |
|
} |
398 |
|
|
399 |
+ |
public boolean isEmpty() { |
400 |
+ |
return AbstractMap.this.isEmpty(); |
401 |
+ |
} |
402 |
+ |
|
403 |
+ |
public void clear() { |
404 |
+ |
AbstractMap.this.clear(); |
405 |
+ |
} |
406 |
+ |
|
407 |
|
public boolean contains(Object v) { |
408 |
|
return AbstractMap.this.containsValue(v); |
409 |
|
} |
420 |
|
/** |
421 |
|
* Compares the specified object with this map for equality. Returns |
422 |
|
* <tt>true</tt> if the given object is also a map and the two maps |
423 |
< |
* represent the same mappings. More formally, two maps <tt>t1</tt> and |
424 |
< |
* <tt>t2</tt> represent the same mappings if |
425 |
< |
* <tt>t1.keySet().equals(t2.keySet())</tt> and for every key <tt>k</tt> |
473 |
< |
* in <tt>t1.keySet()</tt>, <tt> (t1.get(k)==null ? t2.get(k)==null : |
474 |
< |
* t1.get(k).equals(t2.get(k))) </tt>. This ensures that the |
423 |
> |
* represent the same mappings. More formally, two maps <tt>m1</tt> and |
424 |
> |
* <tt>m2</tt> represent the same mappings if |
425 |
> |
* <tt>m1.entrySet().equals(m2.entrySet())</tt>. This ensures that the |
426 |
|
* <tt>equals</tt> method works properly across different implementations |
427 |
< |
* of the map interface.<p> |
427 |
> |
* of the <tt>Map</tt> interface. |
428 |
|
* |
429 |
< |
* This implementation first checks if the specified object is this map; |
429 |
> |
* <p>This implementation first checks if the specified object is this map; |
430 |
|
* if so it returns <tt>true</tt>. Then, it checks if the specified |
431 |
|
* object is a map whose size is identical to the size of this map; if |
432 |
|
* not, it returns <tt>false</tt>. If so, it iterates over this map's |
435 |
|
* fails to contain such a mapping, <tt>false</tt> is returned. If the |
436 |
|
* iteration completes, <tt>true</tt> is returned. |
437 |
|
* |
438 |
< |
* @param o object to be compared for equality with this map. |
439 |
< |
* @return <tt>true</tt> if the specified object is equal to this map. |
438 |
> |
* @param o object to be compared for equality with this map |
439 |
> |
* @return <tt>true</tt> if the specified object is equal to this map |
440 |
|
*/ |
441 |
|
public boolean equals(Object o) { |
442 |
|
if (o == this) |
444 |
|
|
445 |
|
if (!(o instanceof Map)) |
446 |
|
return false; |
447 |
< |
Map<K,V> t = (Map<K,V>) o; |
448 |
< |
if (t.size() != size()) |
447 |
> |
Map<K,V> m = (Map<K,V>) o; |
448 |
> |
if (m.size() != size()) |
449 |
|
return false; |
450 |
|
|
451 |
|
try { |
455 |
|
K key = e.getKey(); |
456 |
|
V value = e.getValue(); |
457 |
|
if (value == null) { |
458 |
< |
if (!(t.get(key)==null && t.containsKey(key))) |
458 |
> |
if (!(m.get(key)==null && m.containsKey(key))) |
459 |
|
return false; |
460 |
|
} else { |
461 |
< |
if (!value.equals(t.get(key))) |
461 |
> |
if (!value.equals(m.get(key))) |
462 |
|
return false; |
463 |
|
} |
464 |
|
} |
474 |
|
/** |
475 |
|
* Returns the hash code value for this map. The hash code of a map is |
476 |
|
* defined to be the sum of the hash codes of each entry in the map's |
477 |
< |
* <tt>entrySet()</tt> view. This ensures that <tt>t1.equals(t2)</tt> |
478 |
< |
* implies that <tt>t1.hashCode()==t2.hashCode()</tt> for any two maps |
479 |
< |
* <tt>t1</tt> and <tt>t2</tt>, as required by the general contract of |
480 |
< |
* Object.hashCode.<p> |
481 |
< |
* |
482 |
< |
* This implementation iterates over <tt>entrySet()</tt>, calling |
483 |
< |
* <tt>hashCode</tt> on each element (entry) in the Collection, and adding |
484 |
< |
* up the results. |
477 |
> |
* <tt>entrySet()</tt> view. This ensures that <tt>m1.equals(m2)</tt> |
478 |
> |
* implies that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps |
479 |
> |
* <tt>m1</tt> and <tt>m2</tt>, as required by the general contract of |
480 |
> |
* {@link Object#hashCode}. |
481 |
> |
* |
482 |
> |
* <p>This implementation iterates over <tt>entrySet()</tt>, calling |
483 |
> |
* {@link Map.Entry#hashCode hashCode()} on each element (entry) in the |
484 |
> |
* set, and adding up the results. |
485 |
|
* |
486 |
< |
* @return the hash code value for this map. |
486 |
> |
* @return the hash code value for this map |
487 |
|
* @see Map.Entry#hashCode() |
537 |
– |
* @see Object#hashCode() |
488 |
|
* @see Object#equals(Object) |
489 |
|
* @see Set#equals(Object) |
490 |
|
*/ |
504 |
|
* <tt>", "</tt> (comma and space). Each key-value mapping is rendered as |
505 |
|
* the key followed by an equals sign (<tt>"="</tt>) followed by the |
506 |
|
* associated value. Keys and values are converted to strings as by |
507 |
< |
* <tt>String.valueOf(Object)</tt>.<p> |
558 |
< |
* |
559 |
< |
* This implementation creates an empty string buffer, appends a left |
560 |
< |
* brace, and iterates over the map's <tt>entrySet</tt> view, appending |
561 |
< |
* the string representation of each <tt>map.entry</tt> in turn. After |
562 |
< |
* appending each entry except the last, the string <tt>", "</tt> is |
563 |
< |
* appended. Finally a right brace is appended. A string is obtained |
564 |
< |
* from the stringbuffer, and returned. |
507 |
> |
* {@link String#valueOf(Object)}. |
508 |
|
* |
509 |
< |
* @return a String representation of this map. |
509 |
> |
* @return a string representation of this map |
510 |
|
*/ |
511 |
|
public String toString() { |
569 |
– |
StringBuffer buf = new StringBuffer(); |
570 |
– |
buf.append("{"); |
571 |
– |
|
512 |
|
Iterator<Entry<K,V>> i = entrySet().iterator(); |
513 |
< |
boolean hasNext = i.hasNext(); |
514 |
< |
while (hasNext) { |
513 |
> |
if (! i.hasNext()) |
514 |
> |
return "{}"; |
515 |
> |
|
516 |
> |
StringBuilder sb = new StringBuilder(); |
517 |
> |
sb.append('{'); |
518 |
> |
for (;;) { |
519 |
|
Entry<K,V> e = i.next(); |
520 |
|
K key = e.getKey(); |
521 |
< |
V value = e.getValue(); |
522 |
< |
if (key == this) |
523 |
< |
buf.append("(this Map)"); |
524 |
< |
else |
525 |
< |
buf.append(key); |
526 |
< |
buf.append("="); |
527 |
< |
if (value == this) |
528 |
< |
buf.append("(this Map)"); |
585 |
< |
else |
586 |
< |
buf.append(value); |
587 |
< |
hasNext = i.hasNext(); |
588 |
< |
if (hasNext) |
589 |
< |
buf.append(", "); |
590 |
< |
} |
591 |
< |
|
592 |
< |
buf.append("}"); |
593 |
< |
return buf.toString(); |
521 |
> |
V value = e.getValue(); |
522 |
> |
sb.append(key == this ? "(this Map)" : key); |
523 |
> |
sb.append('='); |
524 |
> |
sb.append(value == this ? "(this Map)" : value); |
525 |
> |
if (! i.hasNext()) |
526 |
> |
return sb.append('}').toString(); |
527 |
> |
sb.append(", "); |
528 |
> |
} |
529 |
|
} |
530 |
|
|
531 |
|
/** |
532 |
|
* Returns a shallow copy of this <tt>AbstractMap</tt> instance: the keys |
533 |
|
* and values themselves are not cloned. |
534 |
|
* |
535 |
< |
* @return a shallow copy of this map. |
535 |
> |
* @return a shallow copy of this map |
536 |
|
*/ |
537 |
|
protected Object clone() throws CloneNotSupportedException { |
538 |
|
AbstractMap<K,V> result = (AbstractMap<K,V>)super.clone(); |
546 |
|
* Test for equality, checking for nulls. |
547 |
|
*/ |
548 |
|
private static boolean eq(Object o1, Object o2) { |
549 |
< |
return (o1 == null ? o2 == null : o1.equals(o2)); |
549 |
> |
return o1 == null ? o2 == null : o1.equals(o2); |
550 |
|
} |
551 |
|
|
552 |
|
// Implementation Note: SimpleEntry and SimpleImmutableEntry |
563 |
|
* facilitates the process of building custom map |
564 |
|
* implementations. For example, it may be convenient to return |
565 |
|
* arrays of <tt>SimpleEntry</tt> instances in method |
566 |
< |
* <tt>Map.entrySet().toArray</tt> |
566 |
> |
* <tt>Map.entrySet().toArray</tt>. |
567 |
> |
* |
568 |
> |
* @since 1.6 |
569 |
|
*/ |
570 |
< |
public static class SimpleEntry<K,V> implements Entry<K,V> { |
570 |
> |
public static class SimpleEntry<K,V> |
571 |
> |
implements Entry<K,V>, java.io.Serializable |
572 |
> |
{ |
573 |
> |
private static final long serialVersionUID = -8499721149061103585L; |
574 |
> |
|
575 |
|
private final K key; |
576 |
|
private V value; |
577 |
|
|
591 |
|
* Creates an entry representing the same mapping as the |
592 |
|
* specified entry. |
593 |
|
* |
594 |
< |
* @param entry the entry to copy. |
594 |
> |
* @param entry the entry to copy |
595 |
|
*/ |
596 |
|
public SimpleEntry(Entry<? extends K, ? extends V> entry) { |
597 |
|
this.key = entry.getKey(); |
601 |
|
/** |
602 |
|
* Returns the key corresponding to this entry. |
603 |
|
* |
604 |
< |
* @return the key corresponding to this entry. |
604 |
> |
* @return the key corresponding to this entry |
605 |
|
*/ |
606 |
|
public K getKey() { |
607 |
|
return key; |
610 |
|
/** |
611 |
|
* Returns the value corresponding to this entry. |
612 |
|
* |
613 |
< |
* @return the value corresponding to this entry. |
613 |
> |
* @return the value corresponding to this entry |
614 |
|
*/ |
615 |
|
public V getValue() { |
616 |
|
return value; |
620 |
|
* Replaces the value corresponding to this entry with the specified |
621 |
|
* value. |
622 |
|
* |
623 |
< |
* @param value new value to be stored in this entry. |
624 |
< |
* @return the old value corresponding to the entry. |
623 |
> |
* @param value new value to be stored in this entry |
624 |
> |
* @return the old value corresponding to the entry |
625 |
|
*/ |
626 |
|
public V setValue(V value) { |
627 |
|
V oldValue = this.value; |
629 |
|
return oldValue; |
630 |
|
} |
631 |
|
|
632 |
+ |
/** |
633 |
+ |
* Compares the specified object with this entry for equality. |
634 |
+ |
* Returns {@code true} if the given object is also a map entry and |
635 |
+ |
* the two entries represent the same mapping. More formally, two |
636 |
+ |
* entries {@code e1} and {@code e2} represent the same mapping |
637 |
+ |
* if<pre> |
638 |
+ |
* (e1.getKey()==null ? |
639 |
+ |
* e2.getKey()==null : |
640 |
+ |
* e1.getKey().equals(e2.getKey())) |
641 |
+ |
* && |
642 |
+ |
* (e1.getValue()==null ? |
643 |
+ |
* e2.getValue()==null : |
644 |
+ |
* e1.getValue().equals(e2.getValue()))</pre> |
645 |
+ |
* This ensures that the {@code equals} method works properly across |
646 |
+ |
* different implementations of the {@code Map.Entry} interface. |
647 |
+ |
* |
648 |
+ |
* @param o object to be compared for equality with this map entry |
649 |
+ |
* @return {@code true} if the specified object is equal to this map |
650 |
+ |
* entry |
651 |
+ |
* @see #hashCode |
652 |
+ |
*/ |
653 |
|
public boolean equals(Object o) { |
654 |
|
if (!(o instanceof Map.Entry)) |
655 |
|
return false; |
657 |
|
return eq(key, e.getKey()) && eq(value, e.getValue()); |
658 |
|
} |
659 |
|
|
660 |
+ |
/** |
661 |
+ |
* Returns the hash code value for this map entry. The hash code |
662 |
+ |
* of a map entry {@code e} is defined to be: <pre> |
663 |
+ |
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ |
664 |
+ |
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> |
665 |
+ |
* This ensures that {@code e1.equals(e2)} implies that |
666 |
+ |
* {@code e1.hashCode()==e2.hashCode()} for any two Entries |
667 |
+ |
* {@code e1} and {@code e2}, as required by the general |
668 |
+ |
* contract of {@link Object#hashCode}. |
669 |
+ |
* |
670 |
+ |
* @return the hash code value for this map entry |
671 |
+ |
* @see #equals |
672 |
+ |
*/ |
673 |
|
public int hashCode() { |
674 |
< |
return ((key == null) ? 0 : key.hashCode()) ^ |
675 |
< |
((value == null) ? 0 : value.hashCode()); |
674 |
> |
return (key == null ? 0 : key.hashCode()) ^ |
675 |
> |
(value == null ? 0 : value.hashCode()); |
676 |
|
} |
677 |
|
|
678 |
|
/** |
681 |
|
* entry's key followed by the equals character ("<tt>=</tt>") |
682 |
|
* followed by the string representation of this entry's value. |
683 |
|
* |
684 |
< |
* @return a String representation of this map entry. |
684 |
> |
* @return a String representation of this map entry |
685 |
|
*/ |
686 |
|
public String toString() { |
687 |
|
return key + "=" + value; |
690 |
|
} |
691 |
|
|
692 |
|
/** |
693 |
< |
* An Entry maintaining an immutable key and value, This class |
693 |
> |
* An Entry maintaining an immutable key and value. This class |
694 |
|
* does not support method <tt>setValue</tt>. This class may be |
695 |
|
* convenient in methods that return thread-safe snapshots of |
696 |
|
* key-value mappings. |
697 |
+ |
* |
698 |
+ |
* @since 1.6 |
699 |
|
*/ |
700 |
< |
public static class SimpleImmutableEntry<K,V> implements Entry<K,V> { |
700 |
> |
public static class SimpleImmutableEntry<K,V> |
701 |
> |
implements Entry<K,V>, java.io.Serializable |
702 |
> |
{ |
703 |
> |
private static final long serialVersionUID = 7138329143949025153L; |
704 |
> |
|
705 |
|
private final K key; |
706 |
|
private final V value; |
707 |
|
|
721 |
|
* Creates an entry representing the same mapping as the |
722 |
|
* specified entry. |
723 |
|
* |
724 |
< |
* @param entry the entry to copy. |
724 |
> |
* @param entry the entry to copy |
725 |
|
*/ |
726 |
|
public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) { |
727 |
|
this.key = entry.getKey(); |
731 |
|
/** |
732 |
|
* Returns the key corresponding to this entry. |
733 |
|
* |
734 |
< |
* @return the key corresponding to this entry. |
734 |
> |
* @return the key corresponding to this entry |
735 |
|
*/ |
736 |
|
public K getKey() { |
737 |
|
return key; |
740 |
|
/** |
741 |
|
* Returns the value corresponding to this entry. |
742 |
|
* |
743 |
< |
* @return the value corresponding to this entry. |
743 |
> |
* @return the value corresponding to this entry |
744 |
|
*/ |
745 |
|
public V getValue() { |
746 |
|
return value; |
752 |
|
* <tt>UnsupportedOperationException</tt>, as this class implements |
753 |
|
* an <i>immutable</i> map entry. |
754 |
|
* |
755 |
< |
* @param value new value to be stored in this entry. |
755 |
> |
* @param value new value to be stored in this entry |
756 |
|
* @return (Does not return) |
757 |
|
* @throws UnsupportedOperationException always |
758 |
|
*/ |
760 |
|
throw new UnsupportedOperationException(); |
761 |
|
} |
762 |
|
|
763 |
+ |
/** |
764 |
+ |
* Compares the specified object with this entry for equality. |
765 |
+ |
* Returns {@code true} if the given object is also a map entry and |
766 |
+ |
* the two entries represent the same mapping. More formally, two |
767 |
+ |
* entries {@code e1} and {@code e2} represent the same mapping |
768 |
+ |
* if<pre> |
769 |
+ |
* (e1.getKey()==null ? |
770 |
+ |
* e2.getKey()==null : |
771 |
+ |
* e1.getKey().equals(e2.getKey())) |
772 |
+ |
* && |
773 |
+ |
* (e1.getValue()==null ? |
774 |
+ |
* e2.getValue()==null : |
775 |
+ |
* e1.getValue().equals(e2.getValue()))</pre> |
776 |
+ |
* This ensures that the {@code equals} method works properly across |
777 |
+ |
* different implementations of the {@code Map.Entry} interface. |
778 |
+ |
* |
779 |
+ |
* @param o object to be compared for equality with this map entry |
780 |
+ |
* @return {@code true} if the specified object is equal to this map |
781 |
+ |
* entry |
782 |
+ |
* @see #hashCode |
783 |
+ |
*/ |
784 |
|
public boolean equals(Object o) { |
785 |
|
if (!(o instanceof Map.Entry)) |
786 |
|
return false; |
788 |
|
return eq(key, e.getKey()) && eq(value, e.getValue()); |
789 |
|
} |
790 |
|
|
791 |
+ |
/** |
792 |
+ |
* Returns the hash code value for this map entry. The hash code |
793 |
+ |
* of a map entry {@code e} is defined to be: <pre> |
794 |
+ |
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ |
795 |
+ |
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> |
796 |
+ |
* This ensures that {@code e1.equals(e2)} implies that |
797 |
+ |
* {@code e1.hashCode()==e2.hashCode()} for any two Entries |
798 |
+ |
* {@code e1} and {@code e2}, as required by the general |
799 |
+ |
* contract of {@link Object#hashCode}. |
800 |
+ |
* |
801 |
+ |
* @return the hash code value for this map entry |
802 |
+ |
* @see #equals |
803 |
+ |
*/ |
804 |
|
public int hashCode() { |
805 |
< |
return ((key == null) ? 0 : key.hashCode()) ^ |
806 |
< |
((value == null) ? 0 : value.hashCode()); |
805 |
> |
return (key == null ? 0 : key.hashCode()) ^ |
806 |
> |
(value == null ? 0 : value.hashCode()); |
807 |
|
} |
808 |
|
|
809 |
|
/** |
812 |
|
* entry's key followed by the equals character ("<tt>=</tt>") |
813 |
|
* followed by the string representation of this entry's value. |
814 |
|
* |
815 |
< |
* @return a String representation of this map entry. |
815 |
> |
* @return a String representation of this map entry |
816 |
|
*/ |
817 |
|
public String toString() { |
818 |
|
return key + "=" + value; |