ConcurrentMap (Java Platform SE 7 ) (original) (raw)

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:
ConcurrentNavigableMap<K,V>
All Known Implementing Classes:
ConcurrentHashMap, ConcurrentSkipListMap

public interface ConcurrentMap<K,V>
extends Map<K,V>
A Map providing additional atomic
putIfAbsent
,
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](../../../java/util/Map.html "interface in java.util")  
 `[Map.Entry](../../../java/util/Map.Entry.html "interface in java.util")<[K](../../../java/util/Map.Entry.html "type parameter in Map.Entry"),[V](../../../java/util/Map.Entry.html "type parameter in Map.Entry")>`

Method Summary

Methods

Modifier and Type	Method and Description
V	putIfAbsent(K key,V value) If the specified key is not already associated with a value, associate it with the given value.
boolean	remove(Object key,Object value) Removes the entry for a key only if currently mapped to a given value.
V	replace(K key,V value) Replaces the entry for a key only if currently mapped to some value.
boolean	replace(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](../../../java/util/Map.html "interface in java.util")  
   `[clear](../../../java/util/Map.html#clear%28%29), [containsKey](../../../java/util/Map.html#containsKey%28java.lang.Object%29), [containsValue](../../../java/util/Map.html#containsValue%28java.lang.Object%29), [entrySet](../../../java/util/Map.html#entrySet%28%29), [equals](../../../java/util/Map.html#equals%28java.lang.Object%29), [get](../../../java/util/Map.html#get%28java.lang.Object%29), [hashCode](../../../java/util/Map.html#hashCode%28%29), [isEmpty](../../../java/util/Map.html#isEmpty%28%29), [keySet](../../../java/util/Map.html#keySet%28%29), [put](../../../java/util/Map.html#put%28K,%20V%29), [putAll](../../../java/util/Map.html#putAll%28java.util.Map%29), [remove](../../../java/util/Map.html#remove%28java.lang.Object%29), [size](../../../java/util/Map.html#size%28%29), [values](../../../java/util/Map.html#values%28%29)`

Method Detail

 * #### putIfAbsent  
 [V](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") putIfAbsent([K](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") key,  
             [V](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") value)  
 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](../../../java/lang/Object.html "class in java.lang") key,  
              [Object](../../../java/lang/Object.html "class in java.lang") 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](../Collection.html#optional-restrictions))  
 `[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](../Collection.html#optional-restrictions))  
 * #### replace  
 boolean replace([K](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") key,  
               [V](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") oldValue,  
               [V](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") 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  
 [V](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") replace([K](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") key,  
         [V](../../../java/util/concurrent/ConcurrentMap.html "type parameter in ConcurrentMap") value)  
 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

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ConcurrentMap (Java Platform SE 7 ) (original) (raw)

Nested Class Summary

Method Summary

Method Detail