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1.1 |
/* |
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* %W% %E% |
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* |
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jsr166 |
1.6 |
* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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1.1 |
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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*/ |
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package java.util; |
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import java.util.*; // for javadoc (till 6280605 is fixed) |
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1.1 |
import java.util.Map.Entry; |
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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. |
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* |
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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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1.9 |
* should not support the <tt>remove</tt> method. |
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* |
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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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1.9 |
* <tt>remove</tt> method. |
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* |
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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. |
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* |
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1.9 |
* <p>The documentation for each non-abstract methods 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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1.9 |
* map being implemented admits a more efficient implementation. |
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* |
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1.9 |
* <p>This class is a member of the |
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1.1 |
* <a href="{@docRoot}/../guide/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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1.7 |
* @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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* @see Map |
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* @see Collection |
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* @since 1.2 |
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*/ |
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public abstract class AbstractMap<K,V> implements Map<K,V> { |
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/** |
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* Sole constructor. (For invocation by subclass constructors, typically |
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* implicit.) |
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*/ |
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protected AbstractMap() { |
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} |
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// Query Operations |
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/** |
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* {@inheritDoc} |
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* |
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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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1.9 |
* {@inheritDoc} |
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* |
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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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* {@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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1.10 |
* @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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if (value==null) { |
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while (i.hasNext()) { |
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Entry<K,V> e = i.next(); |
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if (e.getValue()==null) |
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return true; |
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} |
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} else { |
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while (i.hasNext()) { |
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Entry<K,V> e = i.next(); |
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if (value.equals(e.getValue())) |
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return true; |
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} |
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} |
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return false; |
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} |
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/** |
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1.9 |
* {@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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1.10 |
* @throws ClassCastException {@inheritDoc} |
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1.9 |
* @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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if (key==null) { |
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while (i.hasNext()) { |
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Entry<K,V> e = i.next(); |
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if (e.getKey()==null) |
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return true; |
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} |
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} else { |
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while (i.hasNext()) { |
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Entry<K,V> e = i.next(); |
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if (key.equals(e.getKey())) |
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return true; |
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} |
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} |
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return false; |
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} |
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/** |
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jsr166 |
1.9 |
* {@inheritDoc} |
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dl |
1.1 |
* |
144 |
jsr166 |
1.9 |
* <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 |
149 |
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* implementations will override this method. |
150 |
jsr166 |
1.7 |
* |
151 |
jsr166 |
1.10 |
* @throws ClassCastException {@inheritDoc} |
152 |
jsr166 |
1.9 |
* @throws NullPointerException {@inheritDoc} |
153 |
dl |
1.1 |
*/ |
154 |
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public V get(Object key) { |
155 |
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Iterator<Entry<K,V>> i = entrySet().iterator(); |
156 |
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if (key==null) { |
157 |
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while (i.hasNext()) { |
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Entry<K,V> e = i.next(); |
159 |
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if (e.getKey()==null) |
160 |
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return e.getValue(); |
161 |
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} |
162 |
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} else { |
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while (i.hasNext()) { |
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Entry<K,V> e = i.next(); |
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if (key.equals(e.getKey())) |
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return e.getValue(); |
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} |
168 |
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} |
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return null; |
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} |
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// Modification Operations |
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/** |
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jsr166 |
1.9 |
* {@inheritDoc} |
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dl |
1.1 |
* |
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jsr166 |
1.9 |
* <p>This implementation always throws an |
179 |
dl |
1.1 |
* <tt>UnsupportedOperationException</tt>. |
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* |
181 |
jsr166 |
1.9 |
* @throws UnsupportedOperationException {@inheritDoc} |
182 |
jsr166 |
1.10 |
* @throws ClassCastException {@inheritDoc} |
183 |
jsr166 |
1.9 |
* @throws NullPointerException {@inheritDoc} |
184 |
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* @throws IllegalArgumentException {@inheritDoc} |
185 |
dl |
1.1 |
*/ |
186 |
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public V put(K key, V value) { |
187 |
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throw new UnsupportedOperationException(); |
188 |
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} |
189 |
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190 |
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/** |
191 |
jsr166 |
1.9 |
* {@inheritDoc} |
192 |
dl |
1.1 |
* |
193 |
jsr166 |
1.9 |
* <p>This implementation iterates over <tt>entrySet()</tt> searching for an |
194 |
dl |
1.1 |
* entry with the specified key. If such an entry is found, its value is |
195 |
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* obtained with its <tt>getValue</tt> operation, the entry is removed |
196 |
jsr166 |
1.7 |
* from the collection (and the backing map) with the iterator's |
197 |
dl |
1.1 |
* <tt>remove</tt> operation, and the saved value is returned. If the |
198 |
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* iteration terminates without finding such an entry, <tt>null</tt> is |
199 |
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* returned. Note that this implementation requires linear time in the |
200 |
jsr166 |
1.9 |
* size of the map; many implementations will override this method. |
201 |
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* |
202 |
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* <p>Note that this implementation throws an |
203 |
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* <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> |
204 |
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* iterator does not support the <tt>remove</tt> method and this map |
205 |
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* contains a mapping for the specified key. |
206 |
dl |
1.1 |
* |
207 |
jsr166 |
1.9 |
* @throws UnsupportedOperationException {@inheritDoc} |
208 |
jsr166 |
1.10 |
* @throws ClassCastException {@inheritDoc} |
209 |
jsr166 |
1.9 |
* @throws NullPointerException {@inheritDoc} |
210 |
dl |
1.1 |
*/ |
211 |
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public V remove(Object key) { |
212 |
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Iterator<Entry<K,V>> i = entrySet().iterator(); |
213 |
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Entry<K,V> correctEntry = null; |
214 |
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if (key==null) { |
215 |
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while (correctEntry==null && i.hasNext()) { |
216 |
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Entry<K,V> e = i.next(); |
217 |
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if (e.getKey()==null) |
218 |
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correctEntry = e; |
219 |
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} |
220 |
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} else { |
221 |
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while (correctEntry==null && i.hasNext()) { |
222 |
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Entry<K,V> e = i.next(); |
223 |
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if (key.equals(e.getKey())) |
224 |
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correctEntry = e; |
225 |
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} |
226 |
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} |
227 |
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228 |
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V oldValue = null; |
229 |
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if (correctEntry !=null) { |
230 |
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oldValue = correctEntry.getValue(); |
231 |
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i.remove(); |
232 |
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} |
233 |
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return oldValue; |
234 |
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} |
235 |
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236 |
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237 |
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// Bulk Operations |
238 |
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|
239 |
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/** |
240 |
jsr166 |
1.9 |
* {@inheritDoc} |
241 |
dl |
1.1 |
* |
242 |
jsr166 |
1.9 |
* <p>This implementation iterates over the specified map's |
243 |
dl |
1.1 |
* <tt>entrySet()</tt> collection, and calls this map's <tt>put</tt> |
244 |
jsr166 |
1.9 |
* operation once for each entry returned by the iteration. |
245 |
dl |
1.1 |
* |
246 |
jsr166 |
1.9 |
* <p>Note that this implementation throws an |
247 |
dl |
1.1 |
* <tt>UnsupportedOperationException</tt> if this map does not support |
248 |
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* the <tt>put</tt> operation and the specified map is nonempty. |
249 |
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* |
250 |
jsr166 |
1.9 |
* @throws UnsupportedOperationException {@inheritDoc} |
251 |
jsr166 |
1.10 |
* @throws ClassCastException {@inheritDoc} |
252 |
jsr166 |
1.9 |
* @throws NullPointerException {@inheritDoc} |
253 |
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* @throws IllegalArgumentException {@inheritDoc} |
254 |
dl |
1.1 |
*/ |
255 |
jsr166 |
1.9 |
public void putAll(Map<? extends K, ? extends V> m) { |
256 |
jsr166 |
1.17 |
for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) |
257 |
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put(e.getKey(), e.getValue()); |
258 |
dl |
1.1 |
} |
259 |
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260 |
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/** |
261 |
jsr166 |
1.9 |
* {@inheritDoc} |
262 |
dl |
1.1 |
* |
263 |
jsr166 |
1.9 |
* <p>This implementation calls <tt>entrySet().clear()</tt>. |
264 |
dl |
1.1 |
* |
265 |
jsr166 |
1.9 |
* <p>Note that this implementation throws an |
266 |
dl |
1.1 |
* <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> |
267 |
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* does not support the <tt>clear</tt> operation. |
268 |
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* |
269 |
jsr166 |
1.9 |
* @throws UnsupportedOperationException {@inheritDoc} |
270 |
dl |
1.1 |
*/ |
271 |
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public void clear() { |
272 |
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entrySet().clear(); |
273 |
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} |
274 |
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275 |
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// Views |
277 |
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278 |
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/** |
279 |
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* Each of these fields are initialized to contain an instance of the |
280 |
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* appropriate view the first time this view is requested. The views are |
281 |
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* stateless, so there's no reason to create more than one of each. |
282 |
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*/ |
283 |
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transient volatile Set<K> keySet = null; |
284 |
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transient volatile Collection<V> values = null; |
285 |
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286 |
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/** |
287 |
jsr166 |
1.9 |
* {@inheritDoc} |
288 |
jsr166 |
1.7 |
* |
289 |
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* <p>This implementation returns a set that subclasses {@link AbstractSet}. |
290 |
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* The subclass's iterator method returns a "wrapper object" over this |
291 |
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* map's <tt>entrySet()</tt> iterator. The <tt>size</tt> method |
292 |
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* delegates to this map's <tt>size</tt> method and the |
293 |
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* <tt>contains</tt> method delegates to this map's |
294 |
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* <tt>containsKey</tt> method. |
295 |
dl |
1.1 |
* |
296 |
jsr166 |
1.7 |
* <p>The set is created the first time this method is called, |
297 |
dl |
1.1 |
* and returned in response to all subsequent calls. No synchronization |
298 |
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* is performed, so there is a slight chance that multiple calls to this |
299 |
jsr166 |
1.7 |
* method will not all return the same set. |
300 |
dl |
1.1 |
*/ |
301 |
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public Set<K> keySet() { |
302 |
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if (keySet == null) { |
303 |
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keySet = new AbstractSet<K>() { |
304 |
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public Iterator<K> iterator() { |
305 |
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return new Iterator<K>() { |
306 |
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private Iterator<Entry<K,V>> i = entrySet().iterator(); |
307 |
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308 |
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public boolean hasNext() { |
309 |
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return i.hasNext(); |
310 |
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} |
311 |
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312 |
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public K next() { |
313 |
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return i.next().getKey(); |
314 |
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} |
315 |
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316 |
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public void remove() { |
317 |
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i.remove(); |
318 |
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} |
319 |
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}; |
320 |
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} |
321 |
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322 |
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public int size() { |
323 |
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return AbstractMap.this.size(); |
324 |
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} |
325 |
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326 |
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public boolean contains(Object k) { |
327 |
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return AbstractMap.this.containsKey(k); |
328 |
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} |
329 |
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}; |
330 |
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} |
331 |
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return keySet; |
332 |
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} |
333 |
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334 |
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/** |
335 |
jsr166 |
1.9 |
* {@inheritDoc} |
336 |
jsr166 |
1.7 |
* |
337 |
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* <p>This implementation returns a collection that subclasses {@link |
338 |
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* AbstractCollection}. The subclass's iterator method returns a |
339 |
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* "wrapper object" over this map's <tt>entrySet()</tt> iterator. |
340 |
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* The <tt>size</tt> method delegates to this map's <tt>size</tt> |
341 |
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* method and the <tt>contains</tt> method delegates to this map's |
342 |
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* <tt>containsValue</tt> method. |
343 |
dl |
1.1 |
* |
344 |
jsr166 |
1.7 |
* <p>The collection is created the first time this method is called, and |
345 |
dl |
1.1 |
* returned in response to all subsequent calls. No synchronization is |
346 |
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* performed, so there is a slight chance that multiple calls to this |
347 |
jsr166 |
1.7 |
* method will not all return the same collection. |
348 |
dl |
1.1 |
*/ |
349 |
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public Collection<V> values() { |
350 |
|
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if (values == null) { |
351 |
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values = new AbstractCollection<V>() { |
352 |
|
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public Iterator<V> iterator() { |
353 |
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return new Iterator<V>() { |
354 |
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private Iterator<Entry<K,V>> i = entrySet().iterator(); |
355 |
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|
356 |
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public boolean hasNext() { |
357 |
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return i.hasNext(); |
358 |
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} |
359 |
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360 |
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public V next() { |
361 |
|
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return i.next().getValue(); |
362 |
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} |
363 |
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364 |
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public void remove() { |
365 |
|
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i.remove(); |
366 |
|
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} |
367 |
|
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}; |
368 |
|
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} |
369 |
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|
370 |
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public int size() { |
371 |
|
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return AbstractMap.this.size(); |
372 |
|
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} |
373 |
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|
374 |
|
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public boolean contains(Object v) { |
375 |
|
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return AbstractMap.this.containsValue(v); |
376 |
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} |
377 |
|
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}; |
378 |
|
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} |
379 |
|
|
return values; |
380 |
|
|
} |
381 |
|
|
|
382 |
|
|
public abstract Set<Entry<K,V>> entrySet(); |
383 |
|
|
|
384 |
|
|
|
385 |
|
|
// Comparison and hashing |
386 |
|
|
|
387 |
|
|
/** |
388 |
jsr166 |
1.14 |
* Compares the specified object with this map for equality. Returns |
389 |
|
|
* <tt>true</tt> if the given object is also a map and the two maps |
390 |
|
|
* represent the same mappings. More formally, two maps <tt>m1</tt> and |
391 |
|
|
* <tt>m2</tt> represent the same mappings if |
392 |
|
|
* <tt>m1.entrySet().equals(m2.entrySet())</tt>. This ensures that the |
393 |
|
|
* <tt>equals</tt> method works properly across different implementations |
394 |
|
|
* of the <tt>Map</tt> interface. |
395 |
dl |
1.1 |
* |
396 |
jsr166 |
1.9 |
* <p>This implementation first checks if the specified object is this map; |
397 |
dl |
1.1 |
* if so it returns <tt>true</tt>. Then, it checks if the specified |
398 |
jsr166 |
1.8 |
* object is a map whose size is identical to the size of this map; if |
399 |
dl |
1.1 |
* not, it returns <tt>false</tt>. If so, it iterates over this map's |
400 |
|
|
* <tt>entrySet</tt> collection, and checks that the specified map |
401 |
|
|
* contains each mapping that this map contains. If the specified map |
402 |
|
|
* fails to contain such a mapping, <tt>false</tt> is returned. If the |
403 |
|
|
* iteration completes, <tt>true</tt> is returned. |
404 |
jsr166 |
1.14 |
* |
405 |
|
|
* @param o object to be compared for equality with this map |
406 |
|
|
* @return <tt>true</tt> if the specified object is equal to this map |
407 |
dl |
1.1 |
*/ |
408 |
|
|
public boolean equals(Object o) { |
409 |
|
|
if (o == this) |
410 |
|
|
return true; |
411 |
|
|
|
412 |
|
|
if (!(o instanceof Map)) |
413 |
|
|
return false; |
414 |
jsr166 |
1.13 |
Map<K,V> m = (Map<K,V>) o; |
415 |
|
|
if (m.size() != size()) |
416 |
dl |
1.1 |
return false; |
417 |
|
|
|
418 |
|
|
try { |
419 |
|
|
Iterator<Entry<K,V>> i = entrySet().iterator(); |
420 |
|
|
while (i.hasNext()) { |
421 |
|
|
Entry<K,V> e = i.next(); |
422 |
|
|
K key = e.getKey(); |
423 |
|
|
V value = e.getValue(); |
424 |
|
|
if (value == null) { |
425 |
jsr166 |
1.13 |
if (!(m.get(key)==null && m.containsKey(key))) |
426 |
dl |
1.1 |
return false; |
427 |
|
|
} else { |
428 |
jsr166 |
1.13 |
if (!value.equals(m.get(key))) |
429 |
dl |
1.1 |
return false; |
430 |
|
|
} |
431 |
|
|
} |
432 |
jsr166 |
1.7 |
} catch (ClassCastException unused) { |
433 |
dl |
1.1 |
return false; |
434 |
jsr166 |
1.7 |
} catch (NullPointerException unused) { |
435 |
dl |
1.1 |
return false; |
436 |
|
|
} |
437 |
|
|
|
438 |
|
|
return true; |
439 |
|
|
} |
440 |
|
|
|
441 |
|
|
/** |
442 |
jsr166 |
1.14 |
* Returns the hash code value for this map. The hash code of a map is |
443 |
|
|
* defined to be the sum of the hash codes of each entry in the map's |
444 |
|
|
* <tt>entrySet()</tt> view. This ensures that <tt>m1.equals(m2)</tt> |
445 |
|
|
* implies that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps |
446 |
|
|
* <tt>m1</tt> and <tt>m2</tt>, as required by the general contract of |
447 |
|
|
* {@link Object#hashCode}. |
448 |
jsr166 |
1.9 |
* |
449 |
|
|
* <p>This implementation iterates over <tt>entrySet()</tt>, calling |
450 |
jsr166 |
1.14 |
* {@link Map.Entry#hashCode hashCode()} on each element (entry) in the |
451 |
|
|
* set, and adding up the results. |
452 |
dl |
1.1 |
* |
453 |
jsr166 |
1.14 |
* @return the hash code value for this map |
454 |
dl |
1.1 |
* @see Map.Entry#hashCode() |
455 |
|
|
* @see Object#equals(Object) |
456 |
|
|
* @see Set#equals(Object) |
457 |
|
|
*/ |
458 |
|
|
public int hashCode() { |
459 |
|
|
int h = 0; |
460 |
|
|
Iterator<Entry<K,V>> i = entrySet().iterator(); |
461 |
|
|
while (i.hasNext()) |
462 |
|
|
h += i.next().hashCode(); |
463 |
|
|
return h; |
464 |
|
|
} |
465 |
|
|
|
466 |
|
|
/** |
467 |
|
|
* Returns a string representation of this map. The string representation |
468 |
|
|
* consists of a list of key-value mappings in the order returned by the |
469 |
|
|
* map's <tt>entrySet</tt> view's iterator, enclosed in braces |
470 |
|
|
* (<tt>"{}"</tt>). Adjacent mappings are separated by the characters |
471 |
|
|
* <tt>", "</tt> (comma and space). Each key-value mapping is rendered as |
472 |
|
|
* the key followed by an equals sign (<tt>"="</tt>) followed by the |
473 |
|
|
* associated value. Keys and values are converted to strings as by |
474 |
jsr166 |
1.17 |
* {@link String#valueOf(Object)}. |
475 |
dl |
1.1 |
* |
476 |
jsr166 |
1.17 |
* @return a string representation of this map |
477 |
dl |
1.1 |
*/ |
478 |
|
|
public String toString() { |
479 |
jsr166 |
1.17 |
Iterator<Entry<K,V>> i = entrySet().iterator(); |
480 |
|
|
if (! i.hasNext()) |
481 |
|
|
return "{}"; |
482 |
|
|
|
483 |
jsr166 |
1.12 |
StringBuilder sb = new StringBuilder(); |
484 |
jsr166 |
1.17 |
sb.append('{'); |
485 |
|
|
for (;;) { |
486 |
dl |
1.1 |
Entry<K,V> e = i.next(); |
487 |
|
|
K key = e.getKey(); |
488 |
jsr166 |
1.17 |
V value = e.getValue(); |
489 |
|
|
sb.append(key == this ? "(this Map)" : key); |
490 |
|
|
sb.append('='); |
491 |
|
|
sb.append(value == this ? "(this Map)" : value); |
492 |
|
|
if (! i.hasNext()) |
493 |
|
|
return sb.append('}').toString(); |
494 |
|
|
sb.append(", "); |
495 |
|
|
} |
496 |
dl |
1.1 |
} |
497 |
jsr166 |
1.7 |
|
498 |
dl |
1.1 |
/** |
499 |
|
|
* Returns a shallow copy of this <tt>AbstractMap</tt> instance: the keys |
500 |
|
|
* and values themselves are not cloned. |
501 |
|
|
* |
502 |
jsr166 |
1.9 |
* @return a shallow copy of this map |
503 |
dl |
1.1 |
*/ |
504 |
|
|
protected Object clone() throws CloneNotSupportedException { |
505 |
|
|
AbstractMap<K,V> result = (AbstractMap<K,V>)super.clone(); |
506 |
|
|
result.keySet = null; |
507 |
|
|
result.values = null; |
508 |
|
|
return result; |
509 |
|
|
} |
510 |
|
|
|
511 |
|
|
/** |
512 |
|
|
* Utility method for SimpleEntry and SimpleImmutableEntry. |
513 |
|
|
* Test for equality, checking for nulls. |
514 |
|
|
*/ |
515 |
|
|
private static boolean eq(Object o1, Object o2) { |
516 |
jsr166 |
1.16 |
return o1 == null ? o2 == null : o1.equals(o2); |
517 |
dl |
1.1 |
} |
518 |
|
|
|
519 |
|
|
// Implementation Note: SimpleEntry and SimpleImmutableEntry |
520 |
|
|
// are distinct unrelated classes, even though they share |
521 |
|
|
// some code. Since you can't add or subtract final-ness |
522 |
dl |
1.3 |
// of a field in a subclass, they can't share representations, |
523 |
dl |
1.1 |
// and the amount of duplicated code is too small to warrant |
524 |
|
|
// exposing a common abstract class. |
525 |
|
|
|
526 |
|
|
|
527 |
|
|
/** |
528 |
|
|
* An Entry maintaining a key and a value. The value may be |
529 |
|
|
* changed using the <tt>setValue</tt> method. This class |
530 |
|
|
* facilitates the process of building custom map |
531 |
|
|
* implementations. For example, it may be convenient to return |
532 |
|
|
* arrays of <tt>SimpleEntry</tt> instances in method |
533 |
jsr166 |
1.16 |
* <tt>Map.entrySet().toArray</tt>. |
534 |
jsr166 |
1.15 |
* |
535 |
|
|
* @since 1.6 |
536 |
dl |
1.1 |
*/ |
537 |
jsr166 |
1.16 |
public static class SimpleEntry<K,V> |
538 |
|
|
implements Entry<K,V>, java.io.Serializable |
539 |
|
|
{ |
540 |
|
|
private static final long serialVersionUID = -8499721149061103585L; |
541 |
|
|
|
542 |
dl |
1.2 |
private final K key; |
543 |
dl |
1.1 |
private V value; |
544 |
|
|
|
545 |
|
|
/** |
546 |
|
|
* Creates an entry representing a mapping from the specified |
547 |
|
|
* key to the specified value. |
548 |
|
|
* |
549 |
|
|
* @param key the key represented by this entry |
550 |
|
|
* @param value the value represented by this entry |
551 |
|
|
*/ |
552 |
|
|
public SimpleEntry(K key, V value) { |
553 |
|
|
this.key = key; |
554 |
|
|
this.value = value; |
555 |
|
|
} |
556 |
|
|
|
557 |
|
|
/** |
558 |
|
|
* Creates an entry representing the same mapping as the |
559 |
|
|
* specified entry. |
560 |
|
|
* |
561 |
jsr166 |
1.11 |
* @param entry the entry to copy |
562 |
dl |
1.1 |
*/ |
563 |
dl |
1.4 |
public SimpleEntry(Entry<? extends K, ? extends V> entry) { |
564 |
dl |
1.1 |
this.key = entry.getKey(); |
565 |
|
|
this.value = entry.getValue(); |
566 |
|
|
} |
567 |
|
|
|
568 |
|
|
/** |
569 |
|
|
* Returns the key corresponding to this entry. |
570 |
|
|
* |
571 |
jsr166 |
1.9 |
* @return the key corresponding to this entry |
572 |
dl |
1.1 |
*/ |
573 |
|
|
public K getKey() { |
574 |
|
|
return key; |
575 |
|
|
} |
576 |
|
|
|
577 |
|
|
/** |
578 |
|
|
* Returns the value corresponding to this entry. |
579 |
|
|
* |
580 |
jsr166 |
1.9 |
* @return the value corresponding to this entry |
581 |
dl |
1.1 |
*/ |
582 |
|
|
public V getValue() { |
583 |
|
|
return value; |
584 |
|
|
} |
585 |
|
|
|
586 |
|
|
/** |
587 |
|
|
* Replaces the value corresponding to this entry with the specified |
588 |
|
|
* value. |
589 |
|
|
* |
590 |
jsr166 |
1.9 |
* @param value new value to be stored in this entry |
591 |
|
|
* @return the old value corresponding to the entry |
592 |
dl |
1.1 |
*/ |
593 |
|
|
public V setValue(V value) { |
594 |
|
|
V oldValue = this.value; |
595 |
|
|
this.value = value; |
596 |
|
|
return oldValue; |
597 |
|
|
} |
598 |
|
|
|
599 |
jsr166 |
1.18 |
/** |
600 |
|
|
* Compares the specified object with this entry for equality. |
601 |
|
|
* Returns {@code true} if the given object is also a map entry and |
602 |
|
|
* the two entries represent the same mapping. More formally, two |
603 |
|
|
* entries {@code e1} and {@code e2} represent the same mapping |
604 |
|
|
* if<pre> |
605 |
|
|
* (e1.getKey()==null ? |
606 |
|
|
* e2.getKey()==null : |
607 |
|
|
* e1.getKey().equals(e2.getKey())) |
608 |
|
|
* && |
609 |
|
|
* (e1.getValue()==null ? |
610 |
|
|
* e2.getValue()==null : |
611 |
|
|
* e1.getValue().equals(e2.getValue()))</pre> |
612 |
|
|
* This ensures that the {@code equals} method works properly across |
613 |
|
|
* different implementations of the {@code Map.Entry} interface. |
614 |
|
|
* |
615 |
|
|
* @param o object to be compared for equality with this map entry |
616 |
|
|
* @return {@code true} if the specified object is equal to this map |
617 |
|
|
* entry |
618 |
|
|
* @see #hashCode |
619 |
|
|
*/ |
620 |
dl |
1.1 |
public boolean equals(Object o) { |
621 |
|
|
if (!(o instanceof Map.Entry)) |
622 |
|
|
return false; |
623 |
|
|
Map.Entry e = (Map.Entry)o; |
624 |
|
|
return eq(key, e.getKey()) && eq(value, e.getValue()); |
625 |
|
|
} |
626 |
|
|
|
627 |
jsr166 |
1.18 |
/** |
628 |
|
|
* Returns the hash code value for this map entry. The hash code |
629 |
|
|
* of a map entry {@code e} is defined to be: <pre> |
630 |
|
|
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ |
631 |
|
|
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> |
632 |
|
|
* This ensures that {@code e1.equals(e2)} implies that |
633 |
|
|
* {@code e1.hashCode()==e2.hashCode()} for any two Entries |
634 |
|
|
* {@code e1} and {@code e2}, as required by the general |
635 |
|
|
* contract of {@link Object#hashCode}. |
636 |
|
|
* |
637 |
|
|
* @return the hash code value for this map entry |
638 |
|
|
* @see #equals |
639 |
|
|
*/ |
640 |
dl |
1.1 |
public int hashCode() { |
641 |
jsr166 |
1.16 |
return (key == null ? 0 : key.hashCode()) ^ |
642 |
|
|
(value == null ? 0 : value.hashCode()); |
643 |
dl |
1.1 |
} |
644 |
|
|
|
645 |
|
|
/** |
646 |
|
|
* Returns a String representation of this map entry. This |
647 |
|
|
* implementation returns the string representation of this |
648 |
|
|
* entry's key followed by the equals character ("<tt>=</tt>") |
649 |
|
|
* followed by the string representation of this entry's value. |
650 |
|
|
* |
651 |
jsr166 |
1.9 |
* @return a String representation of this map entry |
652 |
dl |
1.1 |
*/ |
653 |
|
|
public String toString() { |
654 |
|
|
return key + "=" + value; |
655 |
|
|
} |
656 |
|
|
|
657 |
|
|
} |
658 |
|
|
|
659 |
|
|
/** |
660 |
jsr166 |
1.16 |
* An Entry maintaining an immutable key and value. This class |
661 |
dl |
1.1 |
* does not support method <tt>setValue</tt>. This class may be |
662 |
|
|
* convenient in methods that return thread-safe snapshots of |
663 |
|
|
* key-value mappings. |
664 |
jsr166 |
1.15 |
* |
665 |
|
|
* @since 1.6 |
666 |
dl |
1.1 |
*/ |
667 |
jsr166 |
1.16 |
public static class SimpleImmutableEntry<K,V> |
668 |
|
|
implements Entry<K,V>, java.io.Serializable |
669 |
|
|
{ |
670 |
|
|
private static final long serialVersionUID = 7138329143949025153L; |
671 |
|
|
|
672 |
dl |
1.1 |
private final K key; |
673 |
|
|
private final V value; |
674 |
|
|
|
675 |
|
|
/** |
676 |
|
|
* Creates an entry representing a mapping from the specified |
677 |
|
|
* key to the specified value. |
678 |
|
|
* |
679 |
|
|
* @param key the key represented by this entry |
680 |
|
|
* @param value the value represented by this entry |
681 |
|
|
*/ |
682 |
|
|
public SimpleImmutableEntry(K key, V value) { |
683 |
|
|
this.key = key; |
684 |
|
|
this.value = value; |
685 |
|
|
} |
686 |
|
|
|
687 |
|
|
/** |
688 |
|
|
* Creates an entry representing the same mapping as the |
689 |
|
|
* specified entry. |
690 |
|
|
* |
691 |
jsr166 |
1.9 |
* @param entry the entry to copy |
692 |
dl |
1.1 |
*/ |
693 |
dl |
1.4 |
public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) { |
694 |
dl |
1.1 |
this.key = entry.getKey(); |
695 |
|
|
this.value = entry.getValue(); |
696 |
|
|
} |
697 |
|
|
|
698 |
|
|
/** |
699 |
|
|
* Returns the key corresponding to this entry. |
700 |
|
|
* |
701 |
jsr166 |
1.9 |
* @return the key corresponding to this entry |
702 |
dl |
1.1 |
*/ |
703 |
|
|
public K getKey() { |
704 |
|
|
return key; |
705 |
|
|
} |
706 |
|
|
|
707 |
|
|
/** |
708 |
|
|
* Returns the value corresponding to this entry. |
709 |
|
|
* |
710 |
jsr166 |
1.9 |
* @return the value corresponding to this entry |
711 |
dl |
1.1 |
*/ |
712 |
|
|
public V getValue() { |
713 |
|
|
return value; |
714 |
|
|
} |
715 |
|
|
|
716 |
|
|
/** |
717 |
|
|
* Replaces the value corresponding to this entry with the specified |
718 |
|
|
* value (optional operation). This implementation simply throws |
719 |
|
|
* <tt>UnsupportedOperationException</tt>, as this class implements |
720 |
|
|
* an <i>immutable</i> map entry. |
721 |
|
|
* |
722 |
jsr166 |
1.9 |
* @param value new value to be stored in this entry |
723 |
dl |
1.1 |
* @return (Does not return) |
724 |
|
|
* @throws UnsupportedOperationException always |
725 |
|
|
*/ |
726 |
|
|
public V setValue(V value) { |
727 |
|
|
throw new UnsupportedOperationException(); |
728 |
|
|
} |
729 |
|
|
|
730 |
jsr166 |
1.18 |
/** |
731 |
|
|
* Compares the specified object with this entry for equality. |
732 |
|
|
* Returns {@code true} if the given object is also a map entry and |
733 |
|
|
* the two entries represent the same mapping. More formally, two |
734 |
|
|
* entries {@code e1} and {@code e2} represent the same mapping |
735 |
|
|
* if<pre> |
736 |
|
|
* (e1.getKey()==null ? |
737 |
|
|
* e2.getKey()==null : |
738 |
|
|
* e1.getKey().equals(e2.getKey())) |
739 |
|
|
* && |
740 |
|
|
* (e1.getValue()==null ? |
741 |
|
|
* e2.getValue()==null : |
742 |
|
|
* e1.getValue().equals(e2.getValue()))</pre> |
743 |
|
|
* This ensures that the {@code equals} method works properly across |
744 |
|
|
* different implementations of the {@code Map.Entry} interface. |
745 |
|
|
* |
746 |
|
|
* @param o object to be compared for equality with this map entry |
747 |
|
|
* @return {@code true} if the specified object is equal to this map |
748 |
|
|
* entry |
749 |
|
|
* @see #hashCode |
750 |
|
|
*/ |
751 |
dl |
1.1 |
public boolean equals(Object o) { |
752 |
|
|
if (!(o instanceof Map.Entry)) |
753 |
|
|
return false; |
754 |
|
|
Map.Entry e = (Map.Entry)o; |
755 |
|
|
return eq(key, e.getKey()) && eq(value, e.getValue()); |
756 |
|
|
} |
757 |
|
|
|
758 |
jsr166 |
1.18 |
/** |
759 |
|
|
* Returns the hash code value for this map entry. The hash code |
760 |
|
|
* of a map entry {@code e} is defined to be: <pre> |
761 |
|
|
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ |
762 |
|
|
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> |
763 |
|
|
* This ensures that {@code e1.equals(e2)} implies that |
764 |
|
|
* {@code e1.hashCode()==e2.hashCode()} for any two Entries |
765 |
|
|
* {@code e1} and {@code e2}, as required by the general |
766 |
|
|
* contract of {@link Object#hashCode}. |
767 |
|
|
* |
768 |
|
|
* @return the hash code value for this map entry |
769 |
|
|
* @see #equals |
770 |
|
|
*/ |
771 |
dl |
1.1 |
public int hashCode() { |
772 |
jsr166 |
1.16 |
return (key == null ? 0 : key.hashCode()) ^ |
773 |
|
|
(value == null ? 0 : value.hashCode()); |
774 |
dl |
1.1 |
} |
775 |
|
|
|
776 |
|
|
/** |
777 |
|
|
* Returns a String representation of this map entry. This |
778 |
|
|
* implementation returns the string representation of this |
779 |
|
|
* entry's key followed by the equals character ("<tt>=</tt>") |
780 |
|
|
* followed by the string representation of this entry's value. |
781 |
|
|
* |
782 |
jsr166 |
1.9 |
* @return a String representation of this map entry |
783 |
dl |
1.1 |
*/ |
784 |
|
|
public String toString() { |
785 |
|
|
return key + "=" + value; |
786 |
|
|
} |
787 |
|
|
|
788 |
|
|
} |
789 |
|
|
|
790 |
|
|
} |