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8187443: Forest Consolidation: Move files to unified layout
Reviewed-by: darcy, ihse
This commit is contained in:
parent
270fe13182
commit
3789983e89
56923 changed files with 3 additions and 15727 deletions
857
src/java.base/share/classes/java/util/AbstractMap.java
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857
src/java.base/share/classes/java/util/AbstractMap.java
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/*
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* Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
|
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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||||
*
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* This code is distributed in the hope that it will be useful, but WITHOUT
|
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
||||
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
||||
* version 2 for more details (a copy is included in the LICENSE file that
|
||||
* accompanied this code).
|
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*
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||||
* You should have received a copy of the GNU General Public License version
|
||||
* 2 along with this work; if not, write to the Free Software Foundation,
|
||||
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
||||
*
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||||
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.util;
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import java.util.Map.Entry;
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/**
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* This class provides a skeletal implementation of the {@code Map}
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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 {@code entrySet} 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 {@code AbstractSet}. This set should
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* not support the {@code add} or {@code remove} methods, and its iterator
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* should not support the {@code remove} 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 {@code put} method (which otherwise throws an
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* {@code UnsupportedOperationException}), and the iterator returned by
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* {@code entrySet().iterator()} must additionally implement its
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* {@code remove} 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 {@code Map} interface
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* specification.
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*
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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.
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*
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* <p>This class is a member of the
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* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
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* Java Collections Framework</a>.
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*
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* @param <K> the type of keys maintained by this map
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* @param <V> the type of mapped values
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*
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* @author Josh Bloch
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* @author Neal Gafter
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* @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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* @implSpec
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* This implementation returns {@code entrySet().size()}.
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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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* {@inheritDoc}
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*
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* @implSpec
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* This implementation returns {@code size() == 0}.
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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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* @implSpec
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* This implementation iterates over {@code entrySet()} searching
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* for an entry with the specified value. If such an entry is found,
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* {@code true} is returned. If the iteration terminates without
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* finding such an entry, {@code false} is returned. Note that this
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* implementation requires linear time in the size of the map.
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*
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException {@inheritDoc}
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*/
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public boolean containsValue(Object value) {
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Iterator<Entry<K,V>> i = entrySet().iterator();
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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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* {@inheritDoc}
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*
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* @implSpec
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* This implementation iterates over {@code entrySet()} searching
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* for an entry with the specified key. If such an entry is found,
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* {@code true} is returned. If the iteration terminates without
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* finding such an entry, {@code false} 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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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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* {@inheritDoc}
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*
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* @implSpec
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* This implementation iterates over {@code entrySet()} 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, {@code null} is returned. Note that this
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* implementation requires linear time in the size of the map; many
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* implementations will override this method.
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*
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException {@inheritDoc}
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*/
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public V get(Object key) {
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Iterator<Entry<K,V>> i = entrySet().iterator();
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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 e.getValue();
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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 e.getValue();
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}
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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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* {@inheritDoc}
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*
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* @implSpec
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* This implementation always throws an
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* {@code UnsupportedOperationException}.
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*
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* @throws UnsupportedOperationException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException {@inheritDoc}
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* @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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* {@inheritDoc}
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*
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* @implSpec
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* This implementation iterates over {@code entrySet()} 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 {@code getValue} operation, the entry is removed
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* from the collection (and the backing map) with the iterator's
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* {@code remove} operation, and the saved value is returned. If the
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* iteration terminates without finding such an entry, {@code null} 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.
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*
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* <p>Note that this implementation throws an
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* {@code UnsupportedOperationException} if the {@code entrySet}
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* iterator does not support the {@code remove} method and this map
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* contains a mapping for the specified key.
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*
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* @throws UnsupportedOperationException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException {@inheritDoc}
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*/
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public V remove(Object key) {
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Iterator<Entry<K,V>> i = entrySet().iterator();
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Entry<K,V> correctEntry = null;
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if (key==null) {
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while (correctEntry==null && i.hasNext()) {
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Entry<K,V> e = i.next();
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if (e.getKey()==null)
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correctEntry = e;
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}
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} else {
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while (correctEntry==null && 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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correctEntry = e;
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}
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}
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V oldValue = null;
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if (correctEntry !=null) {
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oldValue = correctEntry.getValue();
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i.remove();
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}
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return oldValue;
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}
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// Bulk Operations
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/**
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* {@inheritDoc}
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*
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* @implSpec
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* This implementation iterates over the specified map's
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* {@code entrySet()} collection, and calls this map's {@code put}
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* operation once for each entry returned by the iteration.
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*
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* <p>Note that this implementation throws an
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* {@code UnsupportedOperationException} if this map does not support
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* the {@code put} operation and the specified map is nonempty.
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*
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* @throws UnsupportedOperationException {@inheritDoc}
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* @throws ClassCastException {@inheritDoc}
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* @throws NullPointerException {@inheritDoc}
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* @throws IllegalArgumentException {@inheritDoc}
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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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* {@inheritDoc}
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*
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* @implSpec
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* This implementation calls {@code entrySet().clear()}.
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*
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* <p>Note that this implementation throws an
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* {@code UnsupportedOperationException} if the {@code entrySet}
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* does not support the {@code clear} operation.
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*
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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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}
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// Views
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/**
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* Each of these fields are initialized to contain an instance of the
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* appropriate view the first time this view is requested. The views are
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* stateless, so there's no reason to create more than one of each.
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*
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* <p>Since there is no synchronization performed while accessing these fields,
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* it is expected that java.util.Map view classes using these fields have
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* no non-final fields (or any fields at all except for outer-this). Adhering
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* to this rule would make the races on these fields benign.
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*
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* <p>It is also imperative that implementations read the field only once,
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* as in:
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*
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* <pre> {@code
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* public Set<K> keySet() {
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* Set<K> ks = keySet; // single racy read
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* if (ks == null) {
|
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* ks = new KeySet();
|
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* keySet = ks;
|
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* }
|
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* return ks;
|
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* }
|
||||
*}</pre>
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*/
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transient Set<K> keySet;
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transient Collection<V> values;
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/**
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* {@inheritDoc}
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*
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* @implSpec
|
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* 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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* map's {@code entrySet()} iterator. The {@code size} method
|
||||
* delegates to this map's {@code size} method and the
|
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* {@code contains} method delegates to this map's
|
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* {@code containsKey} method.
|
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*
|
||||
* <p>The set is created the first time this method is called,
|
||||
* and returned in response to all subsequent calls. No synchronization
|
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* is performed, so there is a slight chance that multiple calls to this
|
||||
* method will not all return the same set.
|
||||
*/
|
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public Set<K> keySet() {
|
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Set<K> ks = keySet;
|
||||
if (ks == null) {
|
||||
ks = new AbstractSet<K>() {
|
||||
public Iterator<K> iterator() {
|
||||
return new Iterator<K>() {
|
||||
private Iterator<Entry<K,V>> i = entrySet().iterator();
|
||||
|
||||
public boolean hasNext() {
|
||||
return i.hasNext();
|
||||
}
|
||||
|
||||
public K next() {
|
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return i.next().getKey();
|
||||
}
|
||||
|
||||
public void remove() {
|
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i.remove();
|
||||
}
|
||||
};
|
||||
}
|
||||
|
||||
public int size() {
|
||||
return AbstractMap.this.size();
|
||||
}
|
||||
|
||||
public boolean isEmpty() {
|
||||
return AbstractMap.this.isEmpty();
|
||||
}
|
||||
|
||||
public void clear() {
|
||||
AbstractMap.this.clear();
|
||||
}
|
||||
|
||||
public boolean contains(Object k) {
|
||||
return AbstractMap.this.containsKey(k);
|
||||
}
|
||||
};
|
||||
keySet = ks;
|
||||
}
|
||||
return ks;
|
||||
}
|
||||
|
||||
/**
|
||||
* {@inheritDoc}
|
||||
*
|
||||
* @implSpec
|
||||
* This implementation returns a collection that subclasses {@link
|
||||
* AbstractCollection}. The subclass's iterator method returns a
|
||||
* "wrapper object" over this map's {@code entrySet()} iterator.
|
||||
* The {@code size} method delegates to this map's {@code size}
|
||||
* method and the {@code contains} method delegates to this map's
|
||||
* {@code containsValue} method.
|
||||
*
|
||||
* <p>The collection is created the first time this method is called, and
|
||||
* returned in response to all subsequent calls. No synchronization is
|
||||
* performed, so there is a slight chance that multiple calls to this
|
||||
* method will not all return the same collection.
|
||||
*/
|
||||
public Collection<V> values() {
|
||||
Collection<V> vals = values;
|
||||
if (vals == null) {
|
||||
vals = new AbstractCollection<V>() {
|
||||
public Iterator<V> iterator() {
|
||||
return new Iterator<V>() {
|
||||
private Iterator<Entry<K,V>> i = entrySet().iterator();
|
||||
|
||||
public boolean hasNext() {
|
||||
return i.hasNext();
|
||||
}
|
||||
|
||||
public V next() {
|
||||
return i.next().getValue();
|
||||
}
|
||||
|
||||
public void remove() {
|
||||
i.remove();
|
||||
}
|
||||
};
|
||||
}
|
||||
|
||||
public int size() {
|
||||
return AbstractMap.this.size();
|
||||
}
|
||||
|
||||
public boolean isEmpty() {
|
||||
return AbstractMap.this.isEmpty();
|
||||
}
|
||||
|
||||
public void clear() {
|
||||
AbstractMap.this.clear();
|
||||
}
|
||||
|
||||
public boolean contains(Object v) {
|
||||
return AbstractMap.this.containsValue(v);
|
||||
}
|
||||
};
|
||||
values = vals;
|
||||
}
|
||||
return vals;
|
||||
}
|
||||
|
||||
public abstract Set<Entry<K,V>> entrySet();
|
||||
|
||||
|
||||
// Comparison and hashing
|
||||
|
||||
/**
|
||||
* Compares the specified object with this map for equality. Returns
|
||||
* {@code true} if the given object is also a map and the two maps
|
||||
* represent the same mappings. More formally, two maps {@code m1} and
|
||||
* {@code m2} represent the same mappings if
|
||||
* {@code m1.entrySet().equals(m2.entrySet())}. This ensures that the
|
||||
* {@code equals} method works properly across different implementations
|
||||
* of the {@code Map} interface.
|
||||
*
|
||||
* @implSpec
|
||||
* This implementation first checks if the specified object is this map;
|
||||
* if so it returns {@code true}. Then, it checks if the specified
|
||||
* object is a map whose size is identical to the size of this map; if
|
||||
* not, it returns {@code false}. If so, it iterates over this map's
|
||||
* {@code entrySet} collection, and checks that the specified map
|
||||
* contains each mapping that this map contains. If the specified map
|
||||
* fails to contain such a mapping, {@code false} is returned. If the
|
||||
* iteration completes, {@code true} is returned.
|
||||
*
|
||||
* @param o object to be compared for equality with this map
|
||||
* @return {@code true} if the specified object is equal to this map
|
||||
*/
|
||||
public boolean equals(Object o) {
|
||||
if (o == this)
|
||||
return true;
|
||||
|
||||
if (!(o instanceof Map))
|
||||
return false;
|
||||
Map<?,?> m = (Map<?,?>) o;
|
||||
if (m.size() != size())
|
||||
return false;
|
||||
|
||||
try {
|
||||
for (Entry<K, V> e : entrySet()) {
|
||||
K key = e.getKey();
|
||||
V value = e.getValue();
|
||||
if (value == null) {
|
||||
if (!(m.get(key) == null && m.containsKey(key)))
|
||||
return false;
|
||||
} else {
|
||||
if (!value.equals(m.get(key)))
|
||||
return false;
|
||||
}
|
||||
}
|
||||
} catch (ClassCastException unused) {
|
||||
return false;
|
||||
} catch (NullPointerException unused) {
|
||||
return false;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the hash code value for this map. The hash code of a map is
|
||||
* defined to be the sum of the hash codes of each entry in the map's
|
||||
* {@code entrySet()} view. This ensures that {@code m1.equals(m2)}
|
||||
* implies that {@code m1.hashCode()==m2.hashCode()} for any two maps
|
||||
* {@code m1} and {@code m2}, as required by the general contract of
|
||||
* {@link Object#hashCode}.
|
||||
*
|
||||
* @implSpec
|
||||
* This implementation iterates over {@code entrySet()}, calling
|
||||
* {@link Map.Entry#hashCode hashCode()} on each element (entry) in the
|
||||
* set, and adding up the results.
|
||||
*
|
||||
* @return the hash code value for this map
|
||||
* @see Map.Entry#hashCode()
|
||||
* @see Object#equals(Object)
|
||||
* @see Set#equals(Object)
|
||||
*/
|
||||
public int hashCode() {
|
||||
int h = 0;
|
||||
for (Entry<K, V> entry : entrySet())
|
||||
h += entry.hashCode();
|
||||
return h;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns a string representation of this map. The string representation
|
||||
* consists of a list of key-value mappings in the order returned by the
|
||||
* map's {@code entrySet} view's iterator, enclosed in braces
|
||||
* ({@code "{}"}). Adjacent mappings are separated by the characters
|
||||
* {@code ", "} (comma and space). Each key-value mapping is rendered as
|
||||
* the key followed by an equals sign ({@code "="}) followed by the
|
||||
* associated value. Keys and values are converted to strings as by
|
||||
* {@link String#valueOf(Object)}.
|
||||
*
|
||||
* @return a string representation of this map
|
||||
*/
|
||||
public String toString() {
|
||||
Iterator<Entry<K,V>> i = entrySet().iterator();
|
||||
if (! i.hasNext())
|
||||
return "{}";
|
||||
|
||||
StringBuilder sb = new StringBuilder();
|
||||
sb.append('{');
|
||||
for (;;) {
|
||||
Entry<K,V> e = i.next();
|
||||
K key = e.getKey();
|
||||
V value = e.getValue();
|
||||
sb.append(key == this ? "(this Map)" : key);
|
||||
sb.append('=');
|
||||
sb.append(value == this ? "(this Map)" : value);
|
||||
if (! i.hasNext())
|
||||
return sb.append('}').toString();
|
||||
sb.append(',').append(' ');
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns a shallow copy of this {@code AbstractMap} instance: the keys
|
||||
* and values themselves are not cloned.
|
||||
*
|
||||
* @return a shallow copy of this map
|
||||
*/
|
||||
protected Object clone() throws CloneNotSupportedException {
|
||||
AbstractMap<?,?> result = (AbstractMap<?,?>)super.clone();
|
||||
result.keySet = null;
|
||||
result.values = null;
|
||||
return result;
|
||||
}
|
||||
|
||||
/**
|
||||
* Utility method for SimpleEntry and SimpleImmutableEntry.
|
||||
* Test for equality, checking for nulls.
|
||||
*
|
||||
* NB: Do not replace with Object.equals until JDK-8015417 is resolved.
|
||||
*/
|
||||
private static boolean eq(Object o1, Object o2) {
|
||||
return o1 == null ? o2 == null : o1.equals(o2);
|
||||
}
|
||||
|
||||
// Implementation Note: SimpleEntry and SimpleImmutableEntry
|
||||
// are distinct unrelated classes, even though they share
|
||||
// some code. Since you can't add or subtract final-ness
|
||||
// of a field in a subclass, they can't share representations,
|
||||
// and the amount of duplicated code is too small to warrant
|
||||
// exposing a common abstract class.
|
||||
|
||||
|
||||
/**
|
||||
* An Entry maintaining a key and a value. The value may be
|
||||
* changed using the {@code setValue} method. This class
|
||||
* facilitates the process of building custom map
|
||||
* implementations. For example, it may be convenient to return
|
||||
* arrays of {@code SimpleEntry} instances in method
|
||||
* {@code Map.entrySet().toArray}.
|
||||
*
|
||||
* @since 1.6
|
||||
*/
|
||||
public static class SimpleEntry<K,V>
|
||||
implements Entry<K,V>, java.io.Serializable
|
||||
{
|
||||
private static final long serialVersionUID = -8499721149061103585L;
|
||||
|
||||
private final K key;
|
||||
private V value;
|
||||
|
||||
/**
|
||||
* Creates an entry representing a mapping from the specified
|
||||
* key to the specified value.
|
||||
*
|
||||
* @param key the key represented by this entry
|
||||
* @param value the value represented by this entry
|
||||
*/
|
||||
public SimpleEntry(K key, V value) {
|
||||
this.key = key;
|
||||
this.value = value;
|
||||
}
|
||||
|
||||
/**
|
||||
* Creates an entry representing the same mapping as the
|
||||
* specified entry.
|
||||
*
|
||||
* @param entry the entry to copy
|
||||
*/
|
||||
public SimpleEntry(Entry<? extends K, ? extends V> entry) {
|
||||
this.key = entry.getKey();
|
||||
this.value = entry.getValue();
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the key corresponding to this entry.
|
||||
*
|
||||
* @return the key corresponding to this entry
|
||||
*/
|
||||
public K getKey() {
|
||||
return key;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the value corresponding to this entry.
|
||||
*
|
||||
* @return the value corresponding to this entry
|
||||
*/
|
||||
public V getValue() {
|
||||
return value;
|
||||
}
|
||||
|
||||
/**
|
||||
* Replaces the value corresponding to this entry with the specified
|
||||
* value.
|
||||
*
|
||||
* @param value new value to be stored in this entry
|
||||
* @return the old value corresponding to the entry
|
||||
*/
|
||||
public V setValue(V value) {
|
||||
V oldValue = this.value;
|
||||
this.value = value;
|
||||
return oldValue;
|
||||
}
|
||||
|
||||
/**
|
||||
* Compares the specified object with this entry for equality.
|
||||
* Returns {@code true} if the given object is also a map entry and
|
||||
* the two entries represent the same mapping. More formally, two
|
||||
* entries {@code e1} and {@code e2} represent the same mapping
|
||||
* if<pre>
|
||||
* (e1.getKey()==null ?
|
||||
* e2.getKey()==null :
|
||||
* e1.getKey().equals(e2.getKey()))
|
||||
* &&
|
||||
* (e1.getValue()==null ?
|
||||
* e2.getValue()==null :
|
||||
* e1.getValue().equals(e2.getValue()))</pre>
|
||||
* This ensures that the {@code equals} method works properly across
|
||||
* different implementations of the {@code Map.Entry} interface.
|
||||
*
|
||||
* @param o object to be compared for equality with this map entry
|
||||
* @return {@code true} if the specified object is equal to this map
|
||||
* entry
|
||||
* @see #hashCode
|
||||
*/
|
||||
public boolean equals(Object o) {
|
||||
if (!(o instanceof Map.Entry))
|
||||
return false;
|
||||
Map.Entry<?,?> e = (Map.Entry<?,?>)o;
|
||||
return eq(key, e.getKey()) && eq(value, e.getValue());
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the hash code value for this map entry. The hash code
|
||||
* of a map entry {@code e} is defined to be: <pre>
|
||||
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^
|
||||
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre>
|
||||
* This ensures that {@code e1.equals(e2)} implies that
|
||||
* {@code e1.hashCode()==e2.hashCode()} for any two Entries
|
||||
* {@code e1} and {@code e2}, as required by the general
|
||||
* contract of {@link Object#hashCode}.
|
||||
*
|
||||
* @return the hash code value for this map entry
|
||||
* @see #equals
|
||||
*/
|
||||
public int hashCode() {
|
||||
return (key == null ? 0 : key.hashCode()) ^
|
||||
(value == null ? 0 : value.hashCode());
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns a String representation of this map entry. This
|
||||
* implementation returns the string representation of this
|
||||
* entry's key followed by the equals character ("{@code =}")
|
||||
* followed by the string representation of this entry's value.
|
||||
*
|
||||
* @return a String representation of this map entry
|
||||
*/
|
||||
public String toString() {
|
||||
return key + "=" + value;
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
/**
|
||||
* An Entry maintaining an immutable key and value. This class
|
||||
* does not support method {@code setValue}. This class may be
|
||||
* convenient in methods that return thread-safe snapshots of
|
||||
* key-value mappings.
|
||||
*
|
||||
* @since 1.6
|
||||
*/
|
||||
public static class SimpleImmutableEntry<K,V>
|
||||
implements Entry<K,V>, java.io.Serializable
|
||||
{
|
||||
private static final long serialVersionUID = 7138329143949025153L;
|
||||
|
||||
private final K key;
|
||||
private final V value;
|
||||
|
||||
/**
|
||||
* Creates an entry representing a mapping from the specified
|
||||
* key to the specified value.
|
||||
*
|
||||
* @param key the key represented by this entry
|
||||
* @param value the value represented by this entry
|
||||
*/
|
||||
public SimpleImmutableEntry(K key, V value) {
|
||||
this.key = key;
|
||||
this.value = value;
|
||||
}
|
||||
|
||||
/**
|
||||
* Creates an entry representing the same mapping as the
|
||||
* specified entry.
|
||||
*
|
||||
* @param entry the entry to copy
|
||||
*/
|
||||
public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) {
|
||||
this.key = entry.getKey();
|
||||
this.value = entry.getValue();
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the key corresponding to this entry.
|
||||
*
|
||||
* @return the key corresponding to this entry
|
||||
*/
|
||||
public K getKey() {
|
||||
return key;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the value corresponding to this entry.
|
||||
*
|
||||
* @return the value corresponding to this entry
|
||||
*/
|
||||
public V getValue() {
|
||||
return value;
|
||||
}
|
||||
|
||||
/**
|
||||
* Replaces the value corresponding to this entry with the specified
|
||||
* value (optional operation). This implementation simply throws
|
||||
* {@code UnsupportedOperationException}, as this class implements
|
||||
* an <i>immutable</i> map entry.
|
||||
*
|
||||
* @param value new value to be stored in this entry
|
||||
* @return (Does not return)
|
||||
* @throws UnsupportedOperationException always
|
||||
*/
|
||||
public V setValue(V value) {
|
||||
throw new UnsupportedOperationException();
|
||||
}
|
||||
|
||||
/**
|
||||
* Compares the specified object with this entry for equality.
|
||||
* Returns {@code true} if the given object is also a map entry and
|
||||
* the two entries represent the same mapping. More formally, two
|
||||
* entries {@code e1} and {@code e2} represent the same mapping
|
||||
* if<pre>
|
||||
* (e1.getKey()==null ?
|
||||
* e2.getKey()==null :
|
||||
* e1.getKey().equals(e2.getKey()))
|
||||
* &&
|
||||
* (e1.getValue()==null ?
|
||||
* e2.getValue()==null :
|
||||
* e1.getValue().equals(e2.getValue()))</pre>
|
||||
* This ensures that the {@code equals} method works properly across
|
||||
* different implementations of the {@code Map.Entry} interface.
|
||||
*
|
||||
* @param o object to be compared for equality with this map entry
|
||||
* @return {@code true} if the specified object is equal to this map
|
||||
* entry
|
||||
* @see #hashCode
|
||||
*/
|
||||
public boolean equals(Object o) {
|
||||
if (!(o instanceof Map.Entry))
|
||||
return false;
|
||||
Map.Entry<?,?> e = (Map.Entry<?,?>)o;
|
||||
return eq(key, e.getKey()) && eq(value, e.getValue());
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the hash code value for this map entry. The hash code
|
||||
* of a map entry {@code e} is defined to be: <pre>
|
||||
* (e.getKey()==null ? 0 : e.getKey().hashCode()) ^
|
||||
* (e.getValue()==null ? 0 : e.getValue().hashCode())</pre>
|
||||
* This ensures that {@code e1.equals(e2)} implies that
|
||||
* {@code e1.hashCode()==e2.hashCode()} for any two Entries
|
||||
* {@code e1} and {@code e2}, as required by the general
|
||||
* contract of {@link Object#hashCode}.
|
||||
*
|
||||
* @return the hash code value for this map entry
|
||||
* @see #equals
|
||||
*/
|
||||
public int hashCode() {
|
||||
return (key == null ? 0 : key.hashCode()) ^
|
||||
(value == null ? 0 : value.hashCode());
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns a String representation of this map entry. This
|
||||
* implementation returns the string representation of this
|
||||
* entry's key followed by the equals character ("{@code =}")
|
||||
* followed by the string representation of this entry's value.
|
||||
*
|
||||
* @return a String representation of this map entry
|
||||
*/
|
||||
public String toString() {
|
||||
return key + "=" + value;
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
}
|
Loading…
Add table
Add a link
Reference in a new issue