| 1 |
/* |
| 2 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
| 3 |
* Expert Group and released to the public domain, as explained at |
| 4 |
* http://creativecommons.org/licenses/publicdomain |
| 5 |
*/ |
| 6 |
|
| 7 |
package java.util.concurrent; |
| 8 |
import java.util.Map; |
| 9 |
|
| 10 |
/** |
| 11 |
* A {@link java.util.Map} providing additional atomic |
| 12 |
* <tt>putIfAbsent</tt>, <tt>remove</tt>, and <tt>replace</tt> methods. |
| 13 |
* |
| 14 |
* <p>This interface is a member of the |
| 15 |
* <a href="{@docRoot}/../guide/collections/index.html"> |
| 16 |
* Java Collections Framework</a>. |
| 17 |
* |
| 18 |
* @since 1.5 |
| 19 |
* @author Doug Lea |
| 20 |
* @param <K> the type of keys maintained by this map |
| 21 |
* @param <V> the type of mapped values |
| 22 |
*/ |
| 23 |
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 |
* if (!map.containsKey(key)) |
| 30 |
* return map.put(key, value); |
| 31 |
* else |
| 32 |
* return map.get(key); |
| 33 |
* </pre> |
| 34 |
* Except that the action is performed atomically. |
| 35 |
* @param key key with which the specified value is to be associated. |
| 36 |
* @param value value to be associated with the specified key. |
| 37 |
* @return previous value associated with specified key, or <tt>null</tt> |
| 38 |
* if there was no mapping for key. A <tt>null</tt> return can |
| 39 |
* also indicate that the map previously associated <tt>null</tt> |
| 40 |
* with the specified key, if the implementation supports |
| 41 |
* <tt>null</tt> values. |
| 42 |
* |
| 43 |
* @throws UnsupportedOperationException if the <tt>put</tt> operation is |
| 44 |
* not supported by this map. |
| 45 |
* @throws ClassCastException if the class of the specified key or value |
| 46 |
* prevents it from being stored in this map. |
| 47 |
* @throws IllegalArgumentException if some aspect of this key or value |
| 48 |
* prevents it from being stored in this map. |
| 49 |
* @throws NullPointerException if this map does not permit <tt>null</tt> |
| 50 |
* keys or values, and the specified key or value is |
| 51 |
* <tt>null</tt>. |
| 52 |
* |
| 53 |
*/ |
| 54 |
V putIfAbsent(K key, V value); |
| 55 |
|
| 56 |
/** |
| 57 |
* Remove entry for key only if currently mapped to given value. |
| 58 |
* Acts as |
| 59 |
* <pre> |
| 60 |
* if ((map.containsKey(key) && map.get(key).equals(value)) { |
| 61 |
* map.remove(key); |
| 62 |
* return true; |
| 63 |
* } else return false; |
| 64 |
* </pre> |
| 65 |
* except that the action is performed atomically. |
| 66 |
* @param key key with which the specified value is associated. |
| 67 |
* @param value value associated with the specified key. |
| 68 |
* @return true if the value was removed, false otherwise |
| 69 |
* @throws UnsupportedOperationException if the <tt>remove</tt> operation is |
| 70 |
* not supported by this map. |
| 71 |
* @throws NullPointerException if this map does not permit <tt>null</tt> |
| 72 |
* keys or values, and the specified key or value is |
| 73 |
* <tt>null</tt>. |
| 74 |
*/ |
| 75 |
boolean remove(Object key, Object value); |
| 76 |
|
| 77 |
|
| 78 |
/** |
| 79 |
* Replace entry for key only if currently mapped to given value. |
| 80 |
* Acts as |
| 81 |
* <pre> |
| 82 |
* if ((map.containsKey(key) && map.get(key).equals(oldValue)) { |
| 83 |
* map.put(key, newValue); |
| 84 |
* return true; |
| 85 |
* } else return false; |
| 86 |
* </pre> |
| 87 |
* except that the action is performed atomically. |
| 88 |
* @param key key with which the specified value is associated. |
| 89 |
* @param oldValue value expected to be associated with the specified key. |
| 90 |
* @param newValue value to be associated with the specified key. |
| 91 |
* @return true if the value was replaced |
| 92 |
* @throws UnsupportedOperationException if the <tt>put</tt> operation is |
| 93 |
* not supported by this map. |
| 94 |
* @throws NullPointerException if this map does not permit <tt>null</tt> |
| 95 |
* keys or values, and the specified key or value is |
| 96 |
* <tt>null</tt>. |
| 97 |
*/ |
| 98 |
boolean replace(K key, V oldValue, V newValue); |
| 99 |
|
| 100 |
/** |
| 101 |
* Replace entry for key only if currently mapped to some value. |
| 102 |
* Acts as |
| 103 |
* <pre> |
| 104 |
* if ((map.containsKey(key)) { |
| 105 |
* return map.put(key, value); |
| 106 |
* } else return null; |
| 107 |
* </pre> |
| 108 |
* except that the action is performed atomically. |
| 109 |
* @param key key with which the specified value is associated. |
| 110 |
* @param value value to be associated with the specified key. |
| 111 |
* @return previous value associated with specified key, or <tt>null</tt> |
| 112 |
* if there was no mapping for key. A <tt>null</tt> return can |
| 113 |
* also indicate that the map previously associated <tt>null</tt> |
| 114 |
* with the specified key, if the implementation supports |
| 115 |
* <tt>null</tt> values. |
| 116 |
* @throws UnsupportedOperationException if the <tt>put</tt> operation is |
| 117 |
* not supported by this map. |
| 118 |
* @throws NullPointerException if this map does not permit <tt>null</tt> |
| 119 |
* keys or values, and the specified key or value is |
| 120 |
* <tt>null</tt>. |
| 121 |
*/ |
| 122 |
V replace(K key, V value); |
| 123 |
|
| 124 |
} |
