1 |
dl |
1.2 |
/* |
2 |
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
|
|
* Expert Group and released to the public domain. Use, modify, and |
4 |
|
|
* redistribute this code in any way without acknowledgement. |
5 |
|
|
*/ |
6 |
|
|
|
7 |
tim |
1.1 |
package java.util.concurrent; |
8 |
|
|
import java.util.Map; |
9 |
|
|
|
10 |
|
|
/** |
11 |
dl |
1.3 |
* A {@link java.util.Map} providing an additional atomic |
12 |
dl |
1.6 |
* <tt>putIfAbsent</tt> and <tt>remove</tt> methods. |
13 |
dl |
1.4 |
* @since 1.5 |
14 |
|
|
* @author Doug Lea |
15 |
|
|
*/ |
16 |
tim |
1.1 |
public interface ConcurrentMap<K, V> extends Map<K, V> { |
17 |
|
|
/** |
18 |
|
|
* If the specified key is not already associated |
19 |
|
|
* with a value, associate it with the given value. |
20 |
|
|
* This is equivalent to |
21 |
|
|
* <pre> |
22 |
dl |
1.5 |
* if (!map.containsKey(key)) |
23 |
|
|
* return map.put(key, value); |
24 |
|
|
* else |
25 |
|
|
* return map.get(key); |
26 |
tim |
1.1 |
* </pre> |
27 |
|
|
* Except that the action is performed atomically. |
28 |
|
|
* @param key key with which the specified value is to be associated. |
29 |
|
|
* @param value value to be associated with the specified key. |
30 |
|
|
* @return previous value associated with specified key, or <tt>null</tt> |
31 |
|
|
* if there was no mapping for key. A <tt>null</tt> return can |
32 |
|
|
* also indicate that the map previously associated <tt>null</tt> |
33 |
|
|
* with the specified key, if the implementation supports |
34 |
|
|
* <tt>null</tt> values. |
35 |
|
|
* |
36 |
|
|
* @throws UnsupportedOperationException if the <tt>put</tt> operation is |
37 |
|
|
* not supported by this map. |
38 |
|
|
* @throws ClassCastException if the class of the specified key or value |
39 |
|
|
* prevents it from being stored in this map. |
40 |
|
|
* @throws IllegalArgumentException if some aspect of this key or value |
41 |
|
|
* prevents it from being stored in this map. |
42 |
|
|
* @throws NullPointerException this map does not permit <tt>null</tt> |
43 |
|
|
* keys or values, and the specified key or value is |
44 |
|
|
* <tt>null</tt>. |
45 |
|
|
* |
46 |
|
|
**/ |
47 |
dl |
1.4 |
V putIfAbsent(K key, V value); |
48 |
dl |
1.6 |
|
49 |
|
|
/** |
50 |
|
|
* Remove entry for key only if currently mapped to given value. |
51 |
|
|
* Acts as |
52 |
|
|
* <pre> |
53 |
|
|
* if (map.get(key) == value) map.remove(key); |
54 |
|
|
* </pre> |
55 |
|
|
* except that the action is performed atomically. |
56 |
|
|
*/ |
57 |
|
|
boolean remove(K key, V value); |
58 |
|
|
|
59 |
tim |
1.1 |
} |