jdk/src/share/classes/java/util/Map.java
author henryjen
Tue, 11 Jun 2013 13:41:38 -0700
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parent 18532 0bbca0914946
child 19074 84a8d23e8f32
permissions -rw-r--r--
8009736: Comparator API cleanup Reviewed-by: psandoz, briangoetz, mduigou, plevart
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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
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 */
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package java.util;
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import java.util.function.BiConsumer;
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import java.util.function.BiFunction;
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import java.util.function.Function;
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import java.io.Serializable;
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/**
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 * An object that maps keys to values.  A map cannot contain duplicate keys;
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 * each key can map to at most one value.
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 *
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 * <p>This interface takes the place of the <tt>Dictionary</tt> class, which
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 * was a totally abstract class rather than an interface.
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 *
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 * <p>The <tt>Map</tt> interface provides three <i>collection views</i>, which
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 * allow a map's contents to be viewed as a set of keys, collection of values,
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 * or set of key-value mappings.  The <i>order</i> of a map is defined as
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 * the order in which the iterators on the map's collection views return their
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 * elements.  Some map implementations, like the <tt>TreeMap</tt> class, make
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 * specific guarantees as to their order; others, like the <tt>HashMap</tt>
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 * class, do not.
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 *
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 * <p>Note: great care must be exercised if mutable objects are used as map
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 * keys.  The behavior of a map is not specified if the value of an object is
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 * changed in a manner that affects <tt>equals</tt> comparisons while the
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 * object is a key in the map.  A special case of this prohibition is that it
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 * is not permissible for a map to contain itself as a key.  While it is
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 * permissible for a map to contain itself as a value, extreme caution is
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 * advised: the <tt>equals</tt> and <tt>hashCode</tt> methods are no longer
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 * well defined on such a map.
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 *
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 * <p>All general-purpose map implementation classes should provide two
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 * "standard" constructors: a void (no arguments) constructor which creates an
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 * empty map, and a constructor with a single argument of type <tt>Map</tt>,
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 * which creates a new map with the same key-value mappings as its argument.
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 * In effect, the latter constructor allows the user to copy any map,
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 * producing an equivalent map of the desired class.  There is no way to
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 * enforce this recommendation (as interfaces cannot contain constructors) but
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 * all of the general-purpose map implementations in the JDK comply.
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 *
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 * <p>The "destructive" methods contained in this interface, that is, the
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 * methods that modify the map on which they operate, are specified to throw
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 * <tt>UnsupportedOperationException</tt> if this map does not support the
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 * operation.  If this is the case, these methods may, but are not required
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 * to, throw an <tt>UnsupportedOperationException</tt> if the invocation would
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 * have no effect on the map.  For example, invoking the {@link #putAll(Map)}
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 * method on an unmodifiable map may, but is not required to, throw the
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 * exception if the map whose mappings are to be "superimposed" is empty.
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 *
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 * <p>Some map implementations have restrictions on the keys and values they
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 * may contain.  For example, some implementations prohibit null keys and
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 * values, and some have restrictions on the types of their keys.  Attempting
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 * to insert an ineligible key or value throws an unchecked exception,
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 * typically <tt>NullPointerException</tt> or <tt>ClassCastException</tt>.
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 * Attempting to query the presence of an ineligible key or value may throw an
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 * exception, or it may simply return false; some implementations will exhibit
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 * the former behavior and some will exhibit the latter.  More generally,
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 * attempting an operation on an ineligible key or value whose completion
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 * would not result in the insertion of an ineligible element into the map may
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 * throw an exception or it may succeed, at the option of the implementation.
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 * Such exceptions are marked as "optional" in the specification for this
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 * interface.
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 *
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 * <p>This interface 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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 * <p>Many methods in Collections Framework interfaces are defined
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 * in terms of the {@link Object#equals(Object) equals} method.  For
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 * example, the specification for the {@link #containsKey(Object)
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 * containsKey(Object key)} method says: "returns <tt>true</tt> if and
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 * only if this map contains a mapping for a key <tt>k</tt> such that
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 * <tt>(key==null ? k==null : key.equals(k))</tt>." This specification should
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 * <i>not</i> be construed to imply that invoking <tt>Map.containsKey</tt>
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 * with a non-null argument <tt>key</tt> will cause <tt>key.equals(k)</tt> to
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 * be invoked for any key <tt>k</tt>.  Implementations are free to
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 * implement optimizations whereby the <tt>equals</tt> invocation is avoided,
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 * for example, by first comparing the hash codes of the two keys.  (The
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 * {@link Object#hashCode()} specification guarantees that two objects with
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 * unequal hash codes cannot be equal.)  More generally, implementations of
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 * the various Collections Framework interfaces are free to take advantage of
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 * the specified behavior of underlying {@link Object} methods wherever the
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 * implementor deems it appropriate.
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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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 * @see HashMap
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 * @see TreeMap
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 * @see Hashtable
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 * @see SortedMap
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 * @see Collection
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 * @see Set
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 * @since 1.2
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 */
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public interface Map<K,V> {
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    // Query Operations
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    /**
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     * Returns the number of key-value mappings in this map.  If the
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     * map contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
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     * <tt>Integer.MAX_VALUE</tt>.
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     *
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     * @return the number of key-value mappings in this map
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     */
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    int size();
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    /**
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     * Returns <tt>true</tt> if this map contains no key-value mappings.
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     *
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     * @return <tt>true</tt> if this map contains no key-value mappings
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     */
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    boolean isEmpty();
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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.  More formally, returns <tt>true</tt> if and only if
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     * this map contains a mapping for a key <tt>k</tt> such that
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     * <tt>(key==null ? k==null : key.equals(k))</tt>.  (There can be
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     * at most one such mapping.)
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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 ClassCastException if the key is of an inappropriate type for
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     *         this map
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     * @throws NullPointerException if the specified key is null and this map
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     *         does not permit null keys
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     */
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    boolean containsKey(Object key);
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    /**
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     * Returns <tt>true</tt> if this map maps one or more keys to the
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     * specified value.  More formally, returns <tt>true</tt> if and only if
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     * this map contains at least one mapping to a value <tt>v</tt> such that
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     * <tt>(value==null ? v==null : value.equals(v))</tt>.  This operation
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     * will probably require time linear in the map size for most
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     * implementations of the <tt>Map</tt> interface.
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     *
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     * @param value value whose presence in this map is to be tested
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     * @return <tt>true</tt> if this map maps one or more keys to the
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     *         specified value
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     * @throws ClassCastException if the value is of an inappropriate type for
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     *         this map
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     * @throws NullPointerException if the specified value is null and this
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     *         map does not permit null values
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     */
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    boolean containsValue(Object value);
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    /**
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     * Returns the value to which the specified key is mapped,
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     * or {@code null} if this map contains no mapping for the key.
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     *
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     * <p>More formally, if this map contains a mapping from a key
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     * {@code k} to a value {@code v} such that {@code (key==null ? k==null :
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     * key.equals(k))}, then this method returns {@code v}; otherwise
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     * it returns {@code null}.  (There can be at most one such mapping.)
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     *
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     * <p>If this map permits null values, then a return value of
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     * {@code null} does not <i>necessarily</i> indicate that the map
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     * contains no mapping for the key; it's also possible that the map
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     * explicitly maps the key to {@code null}.  The {@link #containsKey
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     * containsKey} operation may be used to distinguish these two cases.
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     *
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     * @param key the key whose associated value is to be returned
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     * @return the value to which the specified key is mapped, or
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     *         {@code null} if this map contains no mapping for the key
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     * @throws ClassCastException if the key is of an inappropriate type for
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     *         this map
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     * @throws NullPointerException if the specified key is null and this map
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     *         does not permit null keys
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     */
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    V get(Object key);
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    // Modification Operations
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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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     * the key, the old value is replaced by the specified value.  (A map
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     * <tt>m</tt> is said to contain a mapping for a key <tt>k</tt> if and only
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     * if {@link #containsKey(Object) m.containsKey(k)} would return
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     * <tt>true</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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     * @return the previous value associated with <tt>key</tt>, or
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     *         <tt>null</tt> if there was no mapping for <tt>key</tt>.
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     *         (A <tt>null</tt> return can also indicate that the map
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     *         previously associated <tt>null</tt> with <tt>key</tt>,
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     *         if the implementation supports <tt>null</tt> values.)
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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 NullPointerException if the specified key or value is null
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     *         and this map does not permit null keys or values
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     * @throws IllegalArgumentException if some property of the specified key
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     *         or value prevents it from being stored in this map
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     */
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    V put(K key, V value);
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    /**
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     * Removes the mapping for a key from this map if it is present
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     * (optional operation).   More formally, if this map contains a mapping
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     * from key <tt>k</tt> to value <tt>v</tt> such that
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     * <code>(key==null ?  k==null : key.equals(k))</code>, that mapping
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     * is removed.  (The map can contain at most one such mapping.)
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     *
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     * <p>Returns the value to which this map previously associated the key,
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     * or <tt>null</tt> if the map contained no mapping for the key.
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     *
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     * <p>If this map permits null values, then a return value of
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     * <tt>null</tt> does not <i>necessarily</i> indicate that the map
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     * contained no mapping for the key; it's also possible that the map
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     * explicitly mapped the key to <tt>null</tt>.
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     *
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     * <p>The map will not contain a mapping for the specified key once the
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     * call returns.
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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 <tt>key</tt>, or
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     *         <tt>null</tt> if there was no mapping for <tt>key</tt>.
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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 ClassCastException if the key is of an inappropriate type for
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     *         this map
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     * @throws NullPointerException if the specified key is null and this
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     *         map does not permit null keys
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     * (<a href="Collection.html#optional-restrictions">optional</a>)
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     */
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    V remove(Object key);
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    // Bulk Operations
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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).  The effect of this call is equivalent to that
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     * of calling {@link #put(Object,Object) put(k, v)} on this map once
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     * for each mapping from key <tt>k</tt> to value <tt>v</tt> in the
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     * specified map.  The behavior of this operation is undefined if the
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     * specified map is modified while the operation is in progress.
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     *
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     * @param m mappings to be stored in this map
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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 NullPointerException if the specified map is null, or if
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     *         this map does not permit null keys or values, and the
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     *         specified map contains null keys or values
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     * @throws IllegalArgumentException if some property 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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     */
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    void putAll(Map<? extends K, ? extends V> m);
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    /**
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     * Removes all of the mappings from this map (optional operation).
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     * The map will be empty after this call returns.
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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
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     */
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    void clear();
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    // Views
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    /**
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     * Returns a {@link Set} view of the keys contained in this map.
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     * The set is backed by the map, so changes to the map are
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     * reflected in the set, and vice-versa.  If the map is modified
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     * while an iteration over the set is in progress (except through
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     * the iterator's own <tt>remove</tt> operation), the results of
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     * the iteration are undefined.  The set supports element removal,
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     * which removes the corresponding mapping from the map, via the
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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 <tt>add</tt> or <tt>addAll</tt>
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     * operations.
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     *
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     * @return a set view of the keys contained in this map
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     */
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    Set<K> keySet();
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    /**
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     * Returns a {@link Collection} view of the values contained in this map.
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     * The collection is backed by the map, so changes to the map are
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     * reflected in the collection, and vice-versa.  If the map is
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     * modified while an iteration over the collection is in progress
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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
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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>,
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     * <tt>retainAll</tt> and <tt>clear</tt> operations.  It does not
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     * support the <tt>add</tt> or <tt>addAll</tt> operations.
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     *
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     * @return a collection view of the values contained in this map
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     */
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    Collection<V> values();
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    /**
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     * Returns a {@link Set} view of the mappings contained in this map.
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     * The set is backed by the map, so changes to the map are
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     * reflected in the set, and vice-versa.  If the map is modified
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     * while an iteration over the set is in progress (except through
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     * the iterator's own <tt>remove</tt> operation, or through the
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     * <tt>setValue</tt> operation on a map entry returned by the
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     * iterator) the results of the iteration are undefined.  The set
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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>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
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     * <tt>clear</tt> operations.  It does not support the
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     * <tt>add</tt> or <tt>addAll</tt> operations.
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     *
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     * @return a set view of the mappings contained in this map
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     */
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    Set<Map.Entry<K, V>> entrySet();
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    /**
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     * A map entry (key-value pair).  The <tt>Map.entrySet</tt> method returns
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     * a collection-view of the map, whose elements are of this class.  The
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     * <i>only</i> way to obtain a reference to a map entry is from the
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     * iterator of this collection-view.  These <tt>Map.Entry</tt> objects are
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     * valid <i>only</i> for the duration of the iteration; more formally,
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     * the behavior of a map entry is undefined if the backing map has been
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     * modified after the entry was returned by the iterator, except through
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     * the <tt>setValue</tt> operation on the map entry.
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     *
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     * @see Map#entrySet()
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     * @since 1.2
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     */
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    interface Entry<K,V> {
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        /**
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         * Returns the key corresponding to this entry.
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         *
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         * @return the key corresponding to this entry
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   373
         * @throws IllegalStateException implementations may, but are not
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duke
parents:
diff changeset
   374
         *         required to, throw this exception if the entry has been
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parents:
diff changeset
   375
         *         removed from the backing map.
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parents:
diff changeset
   376
         */
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parents:
diff changeset
   377
        K getKey();
90ce3da70b43 Initial load
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parents:
diff changeset
   378
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parents:
diff changeset
   379
        /**
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duke
parents:
diff changeset
   380
         * Returns the value corresponding to this entry.  If the mapping
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duke
parents:
diff changeset
   381
         * has been removed from the backing map (by the iterator's
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duke
parents:
diff changeset
   382
         * <tt>remove</tt> operation), the results of this call are undefined.
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duke
parents:
diff changeset
   383
         *
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parents:
diff changeset
   384
         * @return the value corresponding to this entry
90ce3da70b43 Initial load
duke
parents:
diff changeset
   385
         * @throws IllegalStateException implementations may, but are not
90ce3da70b43 Initial load
duke
parents:
diff changeset
   386
         *         required to, throw this exception if the entry has been
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duke
parents:
diff changeset
   387
         *         removed from the backing map.
90ce3da70b43 Initial load
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parents:
diff changeset
   388
         */
90ce3da70b43 Initial load
duke
parents:
diff changeset
   389
        V getValue();
90ce3da70b43 Initial load
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parents:
diff changeset
   390
90ce3da70b43 Initial load
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parents:
diff changeset
   391
        /**
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duke
parents:
diff changeset
   392
         * Replaces the value corresponding to this entry with the specified
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parents:
diff changeset
   393
         * value (optional operation).  (Writes through to the map.)  The
90ce3da70b43 Initial load
duke
parents:
diff changeset
   394
         * behavior of this call is undefined if the mapping has already been
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duke
parents:
diff changeset
   395
         * removed from the map (by the iterator's <tt>remove</tt> operation).
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duke
parents:
diff changeset
   396
         *
90ce3da70b43 Initial load
duke
parents:
diff changeset
   397
         * @param value new value to be stored in this entry
90ce3da70b43 Initial load
duke
parents:
diff changeset
   398
         * @return old value corresponding to the entry
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duke
parents:
diff changeset
   399
         * @throws UnsupportedOperationException if the <tt>put</tt> operation
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parents:
diff changeset
   400
         *         is not supported by the backing map
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duke
parents:
diff changeset
   401
         * @throws ClassCastException if the class of the specified value
90ce3da70b43 Initial load
duke
parents:
diff changeset
   402
         *         prevents it from being stored in the backing map
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parents:
diff changeset
   403
         * @throws NullPointerException if the backing map does not permit
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duke
parents:
diff changeset
   404
         *         null values, and the specified value is null
90ce3da70b43 Initial load
duke
parents:
diff changeset
   405
         * @throws IllegalArgumentException if some property of this value
90ce3da70b43 Initial load
duke
parents:
diff changeset
   406
         *         prevents it from being stored in the backing map
90ce3da70b43 Initial load
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parents:
diff changeset
   407
         * @throws IllegalStateException implementations may, but are not
90ce3da70b43 Initial load
duke
parents:
diff changeset
   408
         *         required to, throw this exception if the entry has been
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duke
parents:
diff changeset
   409
         *         removed from the backing map.
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duke
parents:
diff changeset
   410
         */
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duke
parents:
diff changeset
   411
        V setValue(V value);
90ce3da70b43 Initial load
duke
parents:
diff changeset
   412
90ce3da70b43 Initial load
duke
parents:
diff changeset
   413
        /**
90ce3da70b43 Initial load
duke
parents:
diff changeset
   414
         * Compares the specified object with this entry for equality.
90ce3da70b43 Initial load
duke
parents:
diff changeset
   415
         * Returns <tt>true</tt> if the given object is also a map entry and
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duke
parents:
diff changeset
   416
         * the two entries represent the same mapping.  More formally, two
90ce3da70b43 Initial load
duke
parents:
diff changeset
   417
         * entries <tt>e1</tt> and <tt>e2</tt> represent the same mapping
90ce3da70b43 Initial load
duke
parents:
diff changeset
   418
         * if<pre>
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duke
parents:
diff changeset
   419
         *     (e1.getKey()==null ?
90ce3da70b43 Initial load
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parents:
diff changeset
   420
         *      e2.getKey()==null : e1.getKey().equals(e2.getKey()))  &amp;&amp;
90ce3da70b43 Initial load
duke
parents:
diff changeset
   421
         *     (e1.getValue()==null ?
90ce3da70b43 Initial load
duke
parents:
diff changeset
   422
         *      e2.getValue()==null : e1.getValue().equals(e2.getValue()))
90ce3da70b43 Initial load
duke
parents:
diff changeset
   423
         * </pre>
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duke
parents:
diff changeset
   424
         * This ensures that the <tt>equals</tt> method works properly across
90ce3da70b43 Initial load
duke
parents:
diff changeset
   425
         * different implementations of the <tt>Map.Entry</tt> interface.
90ce3da70b43 Initial load
duke
parents:
diff changeset
   426
         *
90ce3da70b43 Initial load
duke
parents:
diff changeset
   427
         * @param o object to be compared for equality with this map entry
90ce3da70b43 Initial load
duke
parents:
diff changeset
   428
         * @return <tt>true</tt> if the specified object is equal to this map
90ce3da70b43 Initial load
duke
parents:
diff changeset
   429
         *         entry
90ce3da70b43 Initial load
duke
parents:
diff changeset
   430
         */
90ce3da70b43 Initial load
duke
parents:
diff changeset
   431
        boolean equals(Object o);
90ce3da70b43 Initial load
duke
parents:
diff changeset
   432
90ce3da70b43 Initial load
duke
parents:
diff changeset
   433
        /**
90ce3da70b43 Initial load
duke
parents:
diff changeset
   434
         * Returns the hash code value for this map entry.  The hash code
90ce3da70b43 Initial load
duke
parents:
diff changeset
   435
         * of a map entry <tt>e</tt> is defined to be: <pre>
90ce3da70b43 Initial load
duke
parents:
diff changeset
   436
         *     (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
90ce3da70b43 Initial load
duke
parents:
diff changeset
   437
         *     (e.getValue()==null ? 0 : e.getValue().hashCode())
90ce3da70b43 Initial load
duke
parents:
diff changeset
   438
         * </pre>
90ce3da70b43 Initial load
duke
parents:
diff changeset
   439
         * This ensures that <tt>e1.equals(e2)</tt> implies that
90ce3da70b43 Initial load
duke
parents:
diff changeset
   440
         * <tt>e1.hashCode()==e2.hashCode()</tt> for any two Entries
90ce3da70b43 Initial load
duke
parents:
diff changeset
   441
         * <tt>e1</tt> and <tt>e2</tt>, as required by the general
90ce3da70b43 Initial load
duke
parents:
diff changeset
   442
         * contract of <tt>Object.hashCode</tt>.
90ce3da70b43 Initial load
duke
parents:
diff changeset
   443
         *
90ce3da70b43 Initial load
duke
parents:
diff changeset
   444
         * @return the hash code value for this map entry
90ce3da70b43 Initial load
duke
parents:
diff changeset
   445
         * @see Object#hashCode()
90ce3da70b43 Initial load
duke
parents:
diff changeset
   446
         * @see Object#equals(Object)
90ce3da70b43 Initial load
duke
parents:
diff changeset
   447
         * @see #equals(Object)
90ce3da70b43 Initial load
duke
parents:
diff changeset
   448
         */
90ce3da70b43 Initial load
duke
parents:
diff changeset
   449
        int hashCode();
18571
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   450
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   451
        /**
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   452
         * Returns a comparator that compares {@link Map.Entry} in natural order on key.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   453
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   454
         * <p>The returned comparator is serializable and throws {@link
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   455
         * NullPointerException} when comparing an entry with a null key.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   456
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   457
         * @param  <K> the {@link Comparable} type of then map keys
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   458
         * @param  <V> the type of the map values
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   459
         * @return a comparator that compares {@link Map.Entry} in natural order on key.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   460
         * @see Comparable
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   461
         */
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   462
        public static <K extends Comparable<? super K>, V> Comparator<Map.Entry<K,V>> comparingByKey() {
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   463
            return (Comparator<Map.Entry<K, V>> & Serializable)
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   464
                (c1, c2) -> c1.getKey().compareTo(c2.getKey());
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   465
        }
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   466
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   467
        /**
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   468
         * Returns a comparator that compares {@link Map.Entry} in natural order on value.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   469
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   470
         * <p>The returned comparator is serializable and throws {@link
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   471
         * NullPointerException} when comparing an entry with null values.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   472
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   473
         * @param <K> the type of the map keys
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   474
         * @param <V> the {@link Comparable} type of the map values
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   475
         * @return a comparator that compares {@link Map.Entry} in natural order on value.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   476
         * @see Comparable
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   477
         */
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   478
        public static <K, V extends Comparable<? super V>> Comparator<Map.Entry<K,V>> comparingByValue() {
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   479
            return (Comparator<Map.Entry<K, V>> & Serializable)
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   480
                (c1, c2) -> c1.getValue().compareTo(c2.getValue());
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   481
        }
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   482
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   483
        /**
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   484
         * Returns a comparator that compares {@link Map.Entry} by key using the given
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   485
         * {@link Comparator}.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   486
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   487
         * <p>The returned comparator is serializable if the specified comparator
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   488
         * is also serializable.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   489
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   490
         * @param  <K> the type of the map keys
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   491
         * @param  <V> the type of the map values
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   492
         * @param  cmp the key {@link Comparator}
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   493
         * @return a comparator that compares {@link Map.Entry} by the key.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   494
         */
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   495
        public static <K, V> Comparator<Map.Entry<K, V>> comparingByKey(Comparator<? super K> cmp) {
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   496
            Objects.requireNonNull(cmp);
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   497
            return (Comparator<Map.Entry<K, V>> & Serializable)
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   498
                (c1, c2) -> cmp.compare(c1.getKey(), c2.getKey());
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   499
        }
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   500
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   501
        /**
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   502
         * Returns a comparator that compares {@link Map.Entry} by value using the given
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   503
         * {@link Comparator}.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   504
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   505
         * <p>The returned comparator is serializable if the specified comparator
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   506
         * is also serializable.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   507
         *
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   508
         * @param  <K> the type of the map keys
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   509
         * @param  <V> the type of the map values
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   510
         * @param  cmp the value {@link Comparator}
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   511
         * @return a comparator that compares {@link Map.Entry} by the value.
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   512
         */
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   513
        public static <K, V> Comparator<Map.Entry<K, V>> comparingByValue(Comparator<? super V> cmp) {
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   514
            Objects.requireNonNull(cmp);
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   515
            return (Comparator<Map.Entry<K, V>> & Serializable)
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   516
                (c1, c2) -> cmp.compare(c1.getValue(), c2.getValue());
8e3cb3c46ae8 8009736: Comparator API cleanup
henryjen
parents: 18532
diff changeset
   517
        }
2
90ce3da70b43 Initial load
duke
parents:
diff changeset
   518
    }
90ce3da70b43 Initial load
duke
parents:
diff changeset
   519
90ce3da70b43 Initial load
duke
parents:
diff changeset
   520
    // Comparison and hashing
90ce3da70b43 Initial load
duke
parents:
diff changeset
   521
90ce3da70b43 Initial load
duke
parents:
diff changeset
   522
    /**
90ce3da70b43 Initial load
duke
parents:
diff changeset
   523
     * Compares the specified object with this map for equality.  Returns
90ce3da70b43 Initial load
duke
parents:
diff changeset
   524
     * <tt>true</tt> if the given object is also a map and the two maps
90ce3da70b43 Initial load
duke
parents:
diff changeset
   525
     * represent the same mappings.  More formally, two maps <tt>m1</tt> and
90ce3da70b43 Initial load
duke
parents:
diff changeset
   526
     * <tt>m2</tt> represent the same mappings if
90ce3da70b43 Initial load
duke
parents:
diff changeset
   527
     * <tt>m1.entrySet().equals(m2.entrySet())</tt>.  This ensures that the
90ce3da70b43 Initial load
duke
parents:
diff changeset
   528
     * <tt>equals</tt> method works properly across different implementations
90ce3da70b43 Initial load
duke
parents:
diff changeset
   529
     * of the <tt>Map</tt> interface.
90ce3da70b43 Initial load
duke
parents:
diff changeset
   530
     *
90ce3da70b43 Initial load
duke
parents:
diff changeset
   531
     * @param o object to be compared for equality with this map
90ce3da70b43 Initial load
duke
parents:
diff changeset
   532
     * @return <tt>true</tt> if the specified object is equal to this map
90ce3da70b43 Initial load
duke
parents:
diff changeset
   533
     */
90ce3da70b43 Initial load
duke
parents:
diff changeset
   534
    boolean equals(Object o);
90ce3da70b43 Initial load
duke
parents:
diff changeset
   535
90ce3da70b43 Initial load
duke
parents:
diff changeset
   536
    /**
90ce3da70b43 Initial load
duke
parents:
diff changeset
   537
     * Returns the hash code value for this map.  The hash code of a map is
90ce3da70b43 Initial load
duke
parents:
diff changeset
   538
     * defined to be the sum of the hash codes of each entry in the map's
90ce3da70b43 Initial load
duke
parents:
diff changeset
   539
     * <tt>entrySet()</tt> view.  This ensures that <tt>m1.equals(m2)</tt>
90ce3da70b43 Initial load
duke
parents:
diff changeset
   540
     * implies that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps
90ce3da70b43 Initial load
duke
parents:
diff changeset
   541
     * <tt>m1</tt> and <tt>m2</tt>, as required by the general contract of
90ce3da70b43 Initial load
duke
parents:
diff changeset
   542
     * {@link Object#hashCode}.
90ce3da70b43 Initial load
duke
parents:
diff changeset
   543
     *
90ce3da70b43 Initial load
duke
parents:
diff changeset
   544
     * @return the hash code value for this map
90ce3da70b43 Initial load
duke
parents:
diff changeset
   545
     * @see Map.Entry#hashCode()
90ce3da70b43 Initial load
duke
parents:
diff changeset
   546
     * @see Object#equals(Object)
90ce3da70b43 Initial load
duke
parents:
diff changeset
   547
     * @see #equals(Object)
90ce3da70b43 Initial load
duke
parents:
diff changeset
   548
     */
90ce3da70b43 Initial load
duke
parents:
diff changeset
   549
    int hashCode();
9503
588cf31d584a 6546713: link the word (optional) in exception specifications to the text which provides explanation and context.
mduigou
parents: 5506
diff changeset
   550
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   551
    // Defaultable methods
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   552
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   553
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   554
    *  Returns the value to which the specified key is mapped,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   555
    *  or {@code defaultValue} if this map contains no mapping
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   556
    *  for the key.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   557
    *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   558
    * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   559
    * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   560
    * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   561
    * concurrency properties.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   562
    *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   563
    * @param key the key whose associated value is to be returned
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   564
    * @return the value to which the specified key is mapped, or
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   565
    * {@code defaultValue} if this map contains no mapping for the key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   566
    * @throws ClassCastException if the key is of an inappropriate type for
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   567
    * this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   568
    * (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   569
    * @throws NullPointerException if the specified key is null and this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   570
    * does not permit null keys
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   571
    * (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   572
    */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   573
    default V getOrDefault(Object key, V defaultValue) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   574
        V v;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   575
        return (((v = get(key)) != null) || containsKey(key))
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   576
            ? v
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   577
            : defaultValue;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   578
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   579
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   580
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   581
     * Performs the given action on each entry in this map, in the order entries
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   582
     * are returned by an entry set iterator (which may be unspecified), until
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   583
     * all entries have been processed or the action throws an {@code Exception}.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   584
     * Exceptions thrown by the action are relayed to the caller.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   585
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   586
     * <p>The default implementation should be overridden by implementations if
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   587
     * they can provide a more performant implementation than an iterator-based
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   588
     * one.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   589
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   590
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   591
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   592
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   593
     * concurrency properties.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   594
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   595
     * @implSpec The default implementation is equivalent to, for this
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   596
     * {@code map}:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   597
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   598
     * for ((Map.Entry<K, V> entry : map.entrySet())
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   599
     *     action.accept(entry.getKey(), entry.getValue());
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   600
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   601
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   602
     * @param action The action to be performed for each entry
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   603
     * @throws NullPointerException if the specified action is null
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   604
     * @throws ConcurrentModificationException if an entry is found to be
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   605
     * removed during iteration
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   606
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   607
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   608
    default void forEach(BiConsumer<? super K, ? super V> action) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   609
        Objects.requireNonNull(action);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   610
        for (Map.Entry<K, V> entry : entrySet()) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   611
            K k;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   612
            V v;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   613
            try {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   614
                k = entry.getKey();
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   615
                v = entry.getValue();
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   616
            } catch(IllegalStateException ise) {
18280
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   617
                // this usually means the entry is no longer in the map.
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   618
                throw new ConcurrentModificationException(ise);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   619
            }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   620
            action.accept(k, v);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   621
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   622
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   623
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   624
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   625
     * Replaces each entry's value with the result of invoking the given
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   626
     * function on that entry, in the order entries are returned by an entry
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   627
     * set iterator, until all entries have been processed or the function
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   628
     * throws an exception.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   629
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   630
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   631
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   632
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   633
     * concurrency properties.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   634
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   635
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   636
     * <p>The default implementation is equivalent to, for this {@code map}:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   637
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   638
     * for ((Map.Entry<K, V> entry : map.entrySet())
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   639
     *     entry.setValue(function.apply(entry.getKey(), entry.getValue()));
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   640
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   641
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   642
     * @param function the function to apply to each entry
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   643
     * @throws UnsupportedOperationException if the {@code set} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   644
     * is not supported by this map's entry set iterator.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   645
     * @throws ClassCastException if the class of a replacement value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   646
     * prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   647
     * @throws NullPointerException if the specified function is null, or the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   648
     * specified replacement value is null, and this map does not permit null
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   649
     * values
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   650
     * @throws ClassCastException if a replacement value is of an inappropriate
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   651
     *         type for this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   652
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   653
     * @throws NullPointerException if function or a replacement value is null,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   654
     *         and this map does not permit null keys or values
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   655
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   656
     * @throws IllegalArgumentException if some property of a replacement value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   657
     *         prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   658
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   659
     * @throws ConcurrentModificationException if an entry is found to be
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   660
     * removed during iteration
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   661
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   662
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   663
    default void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   664
        Objects.requireNonNull(function);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   665
        for (Map.Entry<K, V> entry : entrySet()) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   666
            K k;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   667
            V v;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   668
            try {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   669
                k = entry.getKey();
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   670
                v = entry.getValue();
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   671
            } catch(IllegalStateException ise) {
18280
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   672
                // this usually means the entry is no longer in the map.
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   673
                throw new ConcurrentModificationException(ise);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   674
            }
18280
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   675
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   676
            // ise thrown from function is not a cme.
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   677
            v = function.apply(k, v);
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   678
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   679
            try {
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   680
                entry.setValue(v);
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   681
            } catch(IllegalStateException ise) {
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   682
                // this usually means the entry is no longer in the map.
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   683
                throw new ConcurrentModificationException(ise);
6c3c0ff49eb5 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap, ConcurrentMap
mduigou
parents: 16867
diff changeset
   684
            }
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   685
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   686
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   687
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   688
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   689
     * If the specified key is not already associated with a value (or is mapped
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   690
     * to {@code null}) associates it with the given value and returns
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   691
     * {@code null}, else returns the current value.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   692
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   693
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   694
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   695
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   696
     * concurrency properties.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   697
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   698
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   699
     * The default implementation is equivalent to, for this {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   700
     * map}:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   701
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   702
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   703
     * if (map.get(key) == null)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   704
     *     return map.put(key, value);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   705
     * else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   706
     *     return map.get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   707
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   708
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   709
     * @param key key with which the specified value is to be associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   710
     * @param value value to be associated with the specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   711
     * @return the previous value associated with the specified key, or
18532
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
   712
     *         {@code null} if there was no mapping for the key.
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   713
     *         (A {@code null} return can also indicate that the map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   714
     *         previously associated {@code null} with the key,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   715
     *         if the implementation supports null values.)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   716
     * @throws UnsupportedOperationException if the {@code put} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   717
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   718
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   719
     * @throws ClassCastException if the key or value is of an inappropriate
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   720
     *         type for this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   721
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   722
     * @throws NullPointerException if the specified key or value is null,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   723
     *         and this map does not permit null keys or values
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   724
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   725
     * @throws IllegalArgumentException if some property of the specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   726
     *         or value prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   727
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   728
     * @throws ConcurrentModificationException if a modification of the map is
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   729
     * detected during insertion of the value.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   730
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   731
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   732
    default V putIfAbsent(K key, V value) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   733
        V v = get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   734
        if (v == null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   735
            if (put(key, value) != null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   736
                throw new ConcurrentModificationException();
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   737
            }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   738
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   739
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   740
        return v;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   741
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   742
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   743
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   744
     * Removes the entry for the specified key only if it is currently
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   745
     * mapped to the specified value.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   746
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   747
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   748
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   749
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   750
     * concurrency properties.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   751
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   752
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   753
     * The default implementation is equivalent to, for this {@code map}:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   754
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   755
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   756
     * if (map.containsKey(key) && Objects.equals(map.get(key), value)) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   757
     *     map.remove(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   758
     *     return true;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   759
     * } else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   760
     *     return false;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   761
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   762
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   763
     * @param key key with which the specified value is associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   764
     * @param value value expected to be associated with the specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   765
     * @return {@code true} if the value was removed
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   766
     * @throws UnsupportedOperationException if the {@code remove} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   767
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   768
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   769
     * @throws ClassCastException if the key or value is of an inappropriate
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   770
     *         type for this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   771
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   772
     * @throws NullPointerException if the specified key or value is null,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   773
     *         and this map does not permit null keys or values
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   774
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   775
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   776
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   777
    default boolean remove(Object key, Object value) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   778
        Object curValue = get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   779
        if (!Objects.equals(curValue, value) ||
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   780
            (curValue == null && !containsKey(key))) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   781
            return false;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   782
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   783
        remove(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   784
        return true;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   785
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   786
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   787
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   788
     * Replaces the entry for the specified key only if currently
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   789
     * mapped to the specified value.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   790
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   791
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   792
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   793
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   794
     * concurrency properties.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   795
    *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   796
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   797
     * The default implementation is equivalent to, for this {@code map}:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   798
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   799
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   800
     * if (map.containsKey(key) && Objects.equals(map.get(key), value)) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   801
     *     map.put(key, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   802
     *     return true;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   803
     * } else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   804
     *     return false;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   805
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   806
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   807
     * @param key key with which the specified value is associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   808
     * @param oldValue value expected to be associated with the specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   809
     * @param newValue value to be associated with the specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   810
     * @return {@code true} if the value was replaced
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   811
     * @throws UnsupportedOperationException if the {@code put} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   812
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   813
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   814
     * @throws ClassCastException if the class of a specified key or value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   815
     *         prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   816
     * @throws NullPointerException if a specified key or value is null,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   817
     *         and this map does not permit null keys or values
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   818
     * @throws IllegalArgumentException if some property of a specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   819
     *         or value prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   820
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   821
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   822
    default boolean replace(K key, V oldValue, V newValue) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   823
        Object curValue = get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   824
        if (!Objects.equals(curValue, oldValue) ||
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   825
            (curValue == null && !containsKey(key))) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   826
            return false;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   827
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   828
        put(key, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   829
        return true;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   830
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   831
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   832
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   833
     * Replaces the entry for the specified key only if it is
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   834
     * currently mapped to some value.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   835
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   836
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   837
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   838
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   839
     * concurrency properties.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   840
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   841
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   842
     * The default implementation is equivalent to, for this {@code map}:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   843
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   844
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   845
     * if (map.containsKey(key)) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   846
     *     return map.put(key, value);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   847
     * } else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   848
     *     return null;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   849
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   850
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   851
     * @param key key with which the specified value is associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   852
     * @param value value to be associated with the specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   853
     * @return the previous value associated with the specified key, or
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   854
     *         {@code null} if there was no mapping for the key.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   855
     *         (A {@code null} return can also indicate that the map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   856
     *         previously associated {@code null} with the key,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   857
     *         if the implementation supports null values.)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   858
     * @throws UnsupportedOperationException if the {@code put} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   859
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   860
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   861
     * @throws ClassCastException if the class of the specified key or value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   862
     *         prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   863
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   864
     * @throws NullPointerException if the specified key or value is null,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   865
     *         and this map does not permit null keys or values
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   866
     * @throws IllegalArgumentException if some property of the specified key
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   867
     *         or value prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   868
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   869
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   870
    default V replace(K key, V value) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   871
        return containsKey(key) ? put(key, value) : null;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   872
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   873
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   874
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   875
     * If the specified key is not already associated with a value (or
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   876
     * is mapped to {@code null}), attempts to compute its value using
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   877
     * the given mapping function and enters it into this map unless
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   878
     * {@code null}.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   879
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   880
     * <p>If the function returns {@code null} no mapping is recorded. If
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   881
     * the function itself throws an (unchecked) exception, the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   882
     * exception is rethrown, and no mapping is recorded.  The most
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   883
     * common usage is to construct a new object serving as an initial
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   884
     * mapped value or memoized result, as in:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   885
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   886
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   887
     * map.computeIfAbsent(key, k -> new Value(f(k)));
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   888
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   889
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   890
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   891
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   892
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   893
     * concurrency properties. In particular, all implementations of
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   894
     * subinterface {@link java.util.concurrent.ConcurrentMap} must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   895
     * whether the function is applied once atomically only if the value is not
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   896
     * present.  Any class that permits null values must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   897
     * whether and how this method distinguishes absence from null mappings.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   898
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   899
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   900
     * The default implementation is equivalent to the following
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   901
     * steps for this {@code map}, then returning the current value or
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   902
     * {@code null} if now absent:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   903
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   904
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   905
     * if (map.get(key) == null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   906
     *     V newValue = mappingFunction.apply(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   907
     *     if (newValue != null)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   908
     *         map.putIfAbsent(key, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   909
     * }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   910
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   911
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   912
     * @param key key with which the specified value is to be associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   913
     * @param mappingFunction the function to compute a value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   914
     * @return the current (existing or computed) value associated with
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   915
     *         the specified key, or null if the computed value is null
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   916
     * @throws NullPointerException if the specified key is null and
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   917
     *         this map does not support null keys, or the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   918
     *         mappingFunction is null
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   919
     * @throws UnsupportedOperationException if the {@code put} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   920
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   921
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   922
     * @throws ClassCastException if the class of the specified key or value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   923
     *         prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   924
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   925
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   926
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   927
    default V computeIfAbsent(K key,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   928
            Function<? super K, ? extends V> mappingFunction) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   929
        V v, newValue;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   930
        return ((v = get(key)) == null &&
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   931
                (newValue = mappingFunction.apply(key)) != null &&
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   932
                (v = putIfAbsent(key, newValue)) == null) ? newValue : v;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   933
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   934
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   935
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   936
     * If the value for the specified key is present and non-null, attempts to
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   937
     * compute a new mapping given the key and its current mapped value.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   938
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   939
     * <p>If the function returns {@code null}, the mapping is removed.  If the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   940
     * function itself throws an (unchecked) exception, the exception is
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   941
     * rethrown, and the current mapping is left unchanged.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   942
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   943
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   944
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   945
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   946
     * concurrency properties. In particular, all implementations of
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   947
     * subinterface {@link java.util.concurrent.ConcurrentMap} must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   948
     * whether the function is applied once atomically only if the value is not
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   949
     * present.  Any class that permits null values must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   950
     * whether and how this method distinguishes absence from null mappings.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   951
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   952
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   953
     * The default implementation is equivalent to performing the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   954
     * following steps for this {@code map}, then returning the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   955
     * current value or {@code null} if now absent:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   956
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   957
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   958
     * if (map.get(key) != null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   959
     *     V oldValue = map.get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   960
     *     V newValue = remappingFunction.apply(key, oldValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   961
     *     if (newValue != null)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   962
     *         map.replace(key, oldValue, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   963
     *     else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   964
     *         map.remove(key, oldValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   965
     * }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   966
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   967
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   968
     * In concurrent contexts, the default implementation may retry
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   969
     * these steps when multiple threads attempt updates.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   970
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   971
     * @param key key with which the specified value is to be associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   972
     * @param remappingFunction the function to compute a value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   973
     * @return the new value associated with the specified key, or null if none
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   974
     * @throws NullPointerException if the specified key is null and
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   975
     *         this map does not support null keys, or the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   976
     *         remappingFunction is null
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   977
     * @throws UnsupportedOperationException if the {@code put} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   978
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   979
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   980
     * @throws ClassCastException if the class of the specified key or value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   981
     *         prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   982
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   983
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   984
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   985
    default V computeIfPresent(K key,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   986
            BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   987
        V oldValue;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   988
        while ((oldValue = get(key)) != null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   989
            V newValue = remappingFunction.apply(key, oldValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   990
            if (newValue != null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   991
                if (replace(key, oldValue, newValue))
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   992
                    return newValue;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   993
            } else if (remove(key, oldValue))
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   994
                return null;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   995
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   996
        return oldValue;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   997
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   998
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
   999
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1000
     * Attempts to compute a mapping for the specified key and its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1001
     * current mapped value (or {@code null} if there is no current
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1002
     * mapping). For example, to either create or append a {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1003
     * String msg} to a value mapping:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1004
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1005
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1006
     * map.compute(key, (k, v) -> (v == null) ? msg : v.concat(msg))}</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1007
     * (Method {@link #merge merge()} is often simpler to use for such purposes.)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1008
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1009
     * <p>If the function returns {@code null}, the mapping is removed (or
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1010
     * remains absent if initially absent).  If the function itself throws an
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1011
     * (unchecked) exception, the exception is rethrown, and the current mapping
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1012
     * is left unchanged.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1013
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1014
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1015
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1016
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1017
     * concurrency properties. In particular, all implementations of
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1018
     * subinterface {@link java.util.concurrent.ConcurrentMap} must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1019
     * whether the function is applied once atomically only if the value is not
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1020
     * present.  Any class that permits null values must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1021
     * whether and how this method distinguishes absence from null mappings.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1022
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1023
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1024
     * The default implementation is equivalent to performing the following
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1025
     * steps for this {@code map}, then returning the current value or
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1026
     * {@code null} if absent:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1027
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1028
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1029
     * V oldValue = map.get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1030
     * V newValue = remappingFunction.apply(key, oldValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1031
     * if (oldValue != null ) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1032
     *    if (newValue != null)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1033
     *       map.replace(key, oldValue, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1034
     *    else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1035
     *       map.remove(key, oldValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1036
     * } else {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1037
     *    if (newValue != null)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1038
     *       map.putIfAbsent(key, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1039
     *    else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1040
     *       return null;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1041
     * }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1042
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1043
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1044
     * In concurrent contexts, the default implementation may retry
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1045
     * these steps when multiple threads attempt updates.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1046
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1047
     * @param key key with which the specified value is to be associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1048
     * @param remappingFunction the function to compute a value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1049
     * @return the new value associated with the specified key, or null if none
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1050
     * @throws NullPointerException if the specified key is null and
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1051
     *         this map does not support null keys, or the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1052
     *         remappingFunction is null
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1053
     * @throws UnsupportedOperationException if the {@code put} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1054
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1055
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1056
     * @throws ClassCastException if the class of the specified key or value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1057
     *         prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1058
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1059
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1060
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1061
    default V compute(K key,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1062
            BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1063
        V oldValue = get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1064
        for (;;) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1065
            V newValue = remappingFunction.apply(key, oldValue);
18532
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1066
            if (newValue == null) {
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1067
                // delete mapping
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1068
                if(oldValue != null || containsKey(key)) {
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1069
                    // something to remove
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1070
                    if (remove(key, oldValue)) {
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1071
                        // removed the old value as expected
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1072
                        return null;
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1073
                    }
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1074
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1075
                    // some other value replaced old value. try again.
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1076
                    oldValue = get(key);
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1077
                } else {
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1078
                    // nothing to do. Leave things as they were.
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1079
                    return null;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1080
                }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1081
            } else {
18532
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1082
                // add or replace old mapping
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1083
                if (oldValue != null) {
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1084
                    // replace
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1085
                    if (replace(key, oldValue, newValue)) {
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1086
                        // replaced as expected.
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1087
                        return newValue;
18532
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1088
                    }
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1089
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1090
                    // some other value replaced old value. try again.
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1091
                    oldValue = get(key);
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1092
                } else {
18532
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1093
                    // add (replace if oldValue was null)
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1094
                    if ((oldValue = putIfAbsent(key, newValue)) == null) {
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1095
                        // replaced
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1096
                        return newValue;
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1097
                    }
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1098
0bbca0914946 8017088: Map/HashMap.compute() incorrect with key mapping to null value
mduigou
parents: 18280
diff changeset
  1099
                    // some other value replaced old value. try again.
16867
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1100
                }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1101
            }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1102
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1103
    }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1104
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1105
    /**
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1106
     * If the specified key is not already associated with a value or is
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1107
     * associated with null, associates it with the given value.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1108
     * Otherwise, replaces the value with the results of the given
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1109
     * remapping function, or removes if the result is {@code null}. This
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1110
     * method may be of use when combining multiple mapped values for a key.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1111
     * For example, to either create or append a {@code String msg} to a
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1112
     * value mapping:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1113
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1114
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1115
     * map.merge(key, msg, String::concat)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1116
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1117
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1118
     * <p>If the function returns {@code null}, the mapping is removed (or
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1119
     * remains absent if initially absent).  If the function itself throws an
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1120
     * (unchecked) exception, the exception is rethrown, and the current mapping
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1121
     * is left unchanged.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1122
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1123
     * <p>The default implementation makes no guarantees about synchronization
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1124
     * or atomicity properties of this method. Any implementation providing
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1125
     * atomicity guarantees must override this method and document its
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1126
     * concurrency properties. In particular, all implementations of
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1127
     * subinterface {@link java.util.concurrent.ConcurrentMap} must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1128
     * whether the function is applied once atomically only if the value is not
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1129
     * present.  Any class that permits null values must document
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1130
     * whether and how this method distinguishes absence from null mappings.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1131
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1132
     * @implSpec
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1133
     * The default implementation is equivalent to performing the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1134
     * following steps for this {@code map}, then returning the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1135
     * current value or {@code null} if absent:
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1136
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1137
     * <pre> {@code
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1138
     * V oldValue = map.get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1139
     * V newValue = (oldValue == null) ? value :
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1140
     *              remappingFunction.apply(oldValue, value);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1141
     * if (newValue == null)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1142
     *     map.remove(key, oldValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1143
     * else if (oldValue == null)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1144
     *     map.putIfAbsent(key, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1145
     * else
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1146
     *     map.replace(key, oldValue, newValue);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1147
     * }</pre>
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1148
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1149
     * In concurrent contexts, the default implementation may retry
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1150
     * these steps when multiple threads attempt updates.
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1151
     *
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1152
     * @param key key with which the specified value is to be associated
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1153
     * @param value the value to use if absent
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1154
     * @param remappingFunction the function to recompute a value if present
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1155
     * @return the new value associated with the specified key, or null if none
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1156
     * @throws UnsupportedOperationException if the {@code put} operation
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1157
     *         is not supported by this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1158
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1159
     * @throws ClassCastException if the class of the specified key or value
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1160
     *         prevents it from being stored in this map
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1161
     *         (<a href="Collection.html#optional-restrictions">optional</a>)
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1162
     * @throws NullPointerException if the specified key is null and
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1163
     *         this map does not support null keys, or the
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1164
     *         remappingFunction is null
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1165
     * @since 1.8
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1166
     */
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1167
    default V merge(K key, V value,
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1168
            BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1169
        V oldValue = get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1170
        for (;;) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1171
            if (oldValue != null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1172
                V newValue = remappingFunction.apply(oldValue, value);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1173
                if (newValue != null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1174
                    if (replace(key, oldValue, newValue))
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1175
                        return newValue;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1176
                } else if (remove(key, oldValue)) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1177
                    return null;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1178
                }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1179
                oldValue = get(key);
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1180
            } else {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1181
                if (value == null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1182
                    return null;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1183
                }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1184
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1185
                if ((oldValue = putIfAbsent(key, value)) == null) {
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1186
                    return value;
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1187
                }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1188
            }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1189
        }
76499721c6c1 8004518: Add in-place operations to Map
mduigou
parents: 14342
diff changeset
  1190
    }
2
90ce3da70b43 Initial load
duke
parents:
diff changeset
  1191
}