ConcurrentMap (Java Platform SE 6) (original) (raw)
java.util.concurrent
Interface ConcurrentMap<K,V>
Type Parameters:
K - the type of keys maintained by this map
V - the type of mapped values
All Superinterfaces:
Map<K,V>
All Known Subinterfaces:
All Known Implementing Classes:
ConcurrentHashMap, ConcurrentSkipListMap
public interface ConcurrentMap<K,V>
extends Map<K,V>
A Map providing additional atomicputIfAbsent, remove, and replace methods.
Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into aConcurrentMap as a key or valuehappen-before actions subsequent to the access or removal of that object from the ConcurrentMap in another thread.
This interface is a member of the Java Collections Framework.
Since:
1.5
| Nested Class Summary |
|---|
| Nested classes/interfaces inherited from interface java.util.Map |
|---|
| Map.Entry<K,V> |
| Method Summary | |
|---|---|
| V | [putIfAbsent](../../../java/util/concurrent/ConcurrentMap.html#putIfAbsent%28K, V%29)(K key,V value) If the specified key is not already associated with a value, associate it with the given value. |
| boolean | [remove](../../../java/util/concurrent/ConcurrentMap.html#remove%28java.lang.Object, java.lang.Object%29)(Object key,Object value) Removes the entry for a key only if currently mapped to a given value. |
| V | [replace](../../../java/util/concurrent/ConcurrentMap.html#replace%28K, V%29)(K key,V value) Replaces the entry for a key only if currently mapped to some value. |
| boolean | [replace](../../../java/util/concurrent/ConcurrentMap.html#replace%28K, V, V%29)(K key,V oldValue,V newValue) Replaces the entry for a key only if currently mapped to a given value. |
| Methods inherited from interface java.util.Map |
|---|
| clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, [put](../../../java/util/Map.html#put%28K, V%29), putAll, remove, size, values |
| Method Detail |
|---|
putIfAbsent
If the specified key is not already associated with a value, associate it with the given value. This is equivalent to
if (!map.containsKey(key)) return map.put(key, value); else return map.get(key);
except that the action is performed atomically.
Parameters:
key - key with which the specified value is to be associated
value - value to be associated with the specified key
Returns:
the previous value associated with the specified key, ornull if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)
Throws:
[UnsupportedOperationException](../../../java/lang/UnsupportedOperationException.html "class in java.lang") - if the put operation is not supported by this map
[ClassCastException](../../../java/lang/ClassCastException.html "class in java.lang") - if the class of the specified key or value prevents it from being stored in this map
[NullPointerException](../../../java/lang/NullPointerException.html "class in java.lang") - if the specified key or value is null, and this map does not permit null keys or values
[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang") - if some property of the specified key or value prevents it from being stored in this map
remove
boolean remove(Object key, Object value)
Removes the entry for a key only if currently mapped to a given value. This is equivalent to
if (map.containsKey(key) && map.get(key).equals(value)) { map.remove(key); return true; } else return false;
except that the action is performed atomically.
Parameters:
key - key with which the specified value is associated
value - value expected to be associated with the specified key
Returns:
true if the value was removed
Throws:
[UnsupportedOperationException](../../../java/lang/UnsupportedOperationException.html "class in java.lang") - if the remove operation is not supported by this map
[ClassCastException](../../../java/lang/ClassCastException.html "class in java.lang") - if the key or value is of an inappropriate type for this map (optional)
[NullPointerException](../../../java/lang/NullPointerException.html "class in java.lang") - if the specified key or value is null, and this map does not permit null keys or values (optional)
replace
boolean replace(K key, V oldValue, V newValue)
Replaces the entry for a key only if currently mapped to a given value. This is equivalent to
if (map.containsKey(key) && map.get(key).equals(oldValue)) { map.put(key, newValue); return true; } else return false;
except that the action is performed atomically.
Parameters:
key - key with which the specified value is associated
oldValue - value expected to be associated with the specified key
newValue - value to be associated with the specified key
Returns:
true if the value was replaced
Throws:
[UnsupportedOperationException](../../../java/lang/UnsupportedOperationException.html "class in java.lang") - if the put operation is not supported by this map
[ClassCastException](../../../java/lang/ClassCastException.html "class in java.lang") - if the class of a specified key or value prevents it from being stored in this map
[NullPointerException](../../../java/lang/NullPointerException.html "class in java.lang") - if a specified key or value is null, and this map does not permit null keys or values
[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang") - if some property of a specified key or value prevents it from being stored in this map
replace
Replaces the entry for a key only if currently mapped to some value. This is equivalent to
if (map.containsKey(key)) { return map.put(key, value); } else return null;
except that the action is performed atomically.
Parameters:
key - key with which the specified value is associated
value - value to be associated with the specified key
Returns:
the previous value associated with the specified key, ornull if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key, if the implementation supports null values.)
Throws:
[UnsupportedOperationException](../../../java/lang/UnsupportedOperationException.html "class in java.lang") - if the put operation is not supported by this map
[ClassCastException](../../../java/lang/ClassCastException.html "class in java.lang") - if the class of the specified key or value prevents it from being stored in this map
[NullPointerException](../../../java/lang/NullPointerException.html "class in java.lang") - if the specified key or value is null, and this map does not permit null keys or values
[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang") - if some property of the specified key or value prevents it from being stored in this map
Submit a bug or feature
For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2015, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
Scripting on this page tracks web page traffic, but does not change the content in any way.