util/concurrent/ConcurrentMap.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 */

package java.util.concurrent;
import java.util.Map;

/**
 * A {@link java.util.Map} providing additional atomic
 * <tt>putIfAbsent</tt>, <tt>remove</tt>, and <tt>replace</tt> methods.
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/../guide/collections/index.html">
 * Java Collections Framework</a>.
 *
 * @since 1.5
 * @author Doug Lea
 * @param <K> the type of keys maintained by this map
 * @param <V> the type of mapped values
 */
public interface ConcurrentMap<K, V> extends Map<K, V> {
    /**
     * If the specified key is not already associated
     * with a value, associate it with the given value.
     * This is equivalent to
     * <pre>
     *   if (!map.containsKey(key))
     *       return map.put(key, value);
     *   else
     *       return map.get(key);</pre>
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is to be associated
     * @param value value to be associated with the specified key
     * @return the previous value associated with the specified key, or
     *         <tt>null</tt> if there was no mapping for the key.
     *         (A <tt>null</tt> return can also indicate that the map
     *         previously associated <tt>null</tt> with the key,
     *         if the implementation supports null values.)
     * @throws UnsupportedOperationException if the <tt>put</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the class of the specified key or value
     *         prevents it from being stored in this map
     * @throws NullPointerException if the specified key or value is null,
     *         and this map does not permit null keys or values
     * @throws IllegalArgumentException if some property of the specified key
     *         or value prevents it from being stored in this map
     *
     */
    V putIfAbsent(K key, V value);

    /**
     * Removes the entry for a key only if currently mapped to a given value.
     * This is equivalent to
     * <pre>
     *   if (map.containsKey(key) &amp;&amp; map.get(key).equals(value)) {
     *       map.remove(key);
     *       return true;
     *   } else return false;</pre>
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is associated
     * @param value value expected to be associated with the specified key
     * @return <tt>true</tt> if the value was removed
     * @throws UnsupportedOperationException if the <tt>remove</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the key or value is of an inappropriate
     *         type for this map (optional)
     * @throws NullPointerException if the specified key or value is null,
     *         and this map does not permit null keys or values (optional)
     */
    boolean remove(Object key, Object value);

    /**
     * Replaces the entry for a key only if currently mapped to a given value.
     * This is equivalent to
     * <pre>
     *   if (map.containsKey(key) &amp;&amp; map.get(key).equals(oldValue)) {
     *       map.put(key, newValue);
     *       return true;
     *   } else return false;</pre>
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is associated
     * @param oldValue value expected to be associated with the specified key
     * @param newValue value to be associated with the specified key
     * @return <tt>true</tt> if the value was replaced
     * @throws UnsupportedOperationException if the <tt>put</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the class of a specified key or value
     *         prevents it from being stored in this map
     * @throws NullPointerException if a specified key or value is null,
     *         and this map does not permit null keys or values
     * @throws IllegalArgumentException if some property of a specified key
     *         or value prevents it from being stored in this map
     */
    boolean replace(K key, V oldValue, V newValue);

    /**
     * Replaces the entry for a key only if currently mapped to some value.
     * This is equivalent to
     * <pre>
     *   if (map.containsKey(key)) {
     *       return map.put(key, value);
     *   } else return null;</pre>
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is associated
     * @param value value to be associated with the specified key
     * @return the previous value associated with the specified key, or
     *         <tt>null</tt> if there was no mapping for the key.
     *         (A <tt>null</tt> return can also indicate that the map
     *         previously associated <tt>null</tt> with the key,
     *         if the implementation supports null values.)
     * @throws UnsupportedOperationException if the <tt>put</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the class of the specified key or value
     *         prevents it from being stored in this map
     * @throws NullPointerException if the specified key or value is null,
     *         and this map does not permit null keys or values
     * @throws IllegalArgumentException if some property of the specified key
     *         or value prevents it from being stored in this map
     */
    V replace(K key, V value);
}
Revision:	1.25
Committed:	Wed May 18 00:40:58 2005 UTC (19 years ago) by jsr166
Branch:	MAIN
Changes since 1.24:	+22 -13 lines
Log Message:	doc fixes
#	User	Rev	Content
1	dl	1.2	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3	dl	1.17	* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/licenses/publicdomain
5	dl	1.2	*/
6
7	tim	1.1	package java.util.concurrent;
8			import java.util.Map;
9
10			/**
11	dl	1.11	* A {@link java.util.Map} providing additional atomic
12	dl	1.14	* <tt>putIfAbsent</tt>, <tt>remove</tt>, and <tt>replace</tt> methods.
13	dl	1.19	*
14			* <p>This interface is a member of the
15			* <a href="{@docRoot}/../guide/collections/index.html">
16			* Java Collections Framework</a>.
17	jsr166	1.21	*
18	dl	1.4	* @since 1.5
19			* @author Doug Lea
20	dl	1.13	* @param <K> the type of keys maintained by this map
21	jsr166	1.21	* @param <V> the type of mapped values
22	dl	1.4	*/
23	tim	1.1	public interface ConcurrentMap<K, V> extends Map<K, V> {
24			/**
25			* If the specified key is not already associated
26			* with a value, associate it with the given value.
27			* This is equivalent to
28			* <pre>
29	jsr166	1.21	* if (!map.containsKey(key))
30			* return map.put(key, value);
31	dl	1.5	* else
32	jsr166	1.23	* return map.get(key);</pre>
33	jsr166	1.21	* except that the action is performed atomically.
34			*
35	jsr166	1.24	* @param key key with which the specified value is to be associated
36			* @param value value to be associated with the specified key
37	jsr166	1.25	* @return the previous value associated with the specified key, or
38			* <tt>null</tt> if there was no mapping for the key.
39	jsr166	1.24	* (A <tt>null</tt> return can also indicate that the map
40	jsr166	1.25	* previously associated <tt>null</tt> with the key,
41			* if the implementation supports null values.)
42	jsr166	1.22	* @throws UnsupportedOperationException if the <tt>put</tt> operation
43	jsr166	1.24	* is not supported by this map
44	tim	1.1	* @throws ClassCastException if the class of the specified key or value
45	jsr166	1.24	* prevents it from being stored in this map
46			* @throws NullPointerException if the specified key or value is null,
47			* and this map does not permit null keys or values
48			* @throws IllegalArgumentException if some property of the specified key
49			* or value prevents it from being stored in this map
50	tim	1.1	*
51	dl	1.18	*/
52	dl	1.4	V putIfAbsent(K key, V value);
53	dl	1.6
54			/**
55	jsr166	1.21	* Removes the entry for a key only if currently mapped to a given value.
56			* This is equivalent to
57			* <pre>
58	jsr166	1.24	* if (map.containsKey(key) && map.get(key).equals(value)) {
59	jsr166	1.21	* map.remove(key);
60			* return true;
61	jsr166	1.23	* } else return false;</pre>
62	dl	1.6	* except that the action is performed atomically.
63	jsr166	1.21	*
64	jsr166	1.24	* @param key key with which the specified value is associated
65	jsr166	1.25	* @param value value expected to be associated with the specified key
66			* @return <tt>true</tt> if the value was removed
67	jsr166	1.22	* @throws UnsupportedOperationException if the <tt>remove</tt> operation
68	jsr166	1.24	* is not supported by this map
69	jsr166	1.25	* @throws ClassCastException if the key or value is of an inappropriate
70			* type for this map (optional)
71	jsr166	1.24	* @throws NullPointerException if the specified key or value is null,
72	jsr166	1.25	* and this map does not permit null keys or values (optional)
73	dl	1.6	*/
74	dl	1.7	boolean remove(Object key, Object value);
75	dl	1.14
76			/**
77	jsr166	1.21	* Replaces the entry for a key only if currently mapped to a given value.
78			* This is equivalent to
79			* <pre>
80	jsr166	1.24	* if (map.containsKey(key) && map.get(key).equals(oldValue)) {
81	jsr166	1.21	* map.put(key, newValue);
82			* return true;
83	jsr166	1.23	* } else return false;</pre>
84	dl	1.14	* except that the action is performed atomically.
85	jsr166	1.21	*
86	jsr166	1.24	* @param key key with which the specified value is associated
87			* @param oldValue value expected to be associated with the specified key
88			* @param newValue value to be associated with the specified key
89	jsr166	1.25	* @return <tt>true</tt> if the value was replaced
90	jsr166	1.22	* @throws UnsupportedOperationException if the <tt>put</tt> operation
91	jsr166	1.24	* is not supported by this map
92	jsr166	1.25	* @throws ClassCastException if the class of a specified key or value
93			* prevents it from being stored in this map
94	jsr166	1.24	* @throws NullPointerException if a specified key or value is null,
95			* and this map does not permit null keys or values
96	jsr166	1.25	* @throws IllegalArgumentException if some property of a specified key
97			* or value prevents it from being stored in this map
98	dl	1.14	*/
99			boolean replace(K key, V oldValue, V newValue);
100	dl	1.6
101	dl	1.15	/**
102	jsr166	1.21	* Replaces the entry for a key only if currently mapped to some value.
103			* This is equivalent to
104			* <pre>
105			* if (map.containsKey(key)) {
106			* return map.put(key, value);
107	jsr166	1.23	* } else return null;</pre>
108	dl	1.15	* except that the action is performed atomically.
109	jsr166	1.21	*
110	jsr166	1.24	* @param key key with which the specified value is associated
111			* @param value value to be associated with the specified key
112	jsr166	1.25	* @return the previous value associated with the specified key, or
113			* <tt>null</tt> if there was no mapping for the key.
114	jsr166	1.24	* (A <tt>null</tt> return can also indicate that the map
115	jsr166	1.25	* previously associated <tt>null</tt> with the key,
116			* if the implementation supports null values.)
117	jsr166	1.22	* @throws UnsupportedOperationException if the <tt>put</tt> operation
118	jsr166	1.24	* is not supported by this map
119	jsr166	1.25	* @throws ClassCastException if the class of the specified key or value
120			* prevents it from being stored in this map
121	jsr166	1.24	* @throws NullPointerException if the specified key or value is null,
122			* and this map does not permit null keys or values
123	jsr166	1.25	* @throws IllegalArgumentException if some property of the specified key
124			* or value prevents it from being stored in this map
125	dl	1.15	*/
126	dl	1.16	V replace(K key, V value);
127	tim	1.1	}