| java.util.concurrent.ConcurrentMap<K, V> |
 Known Indirect Subclasses
|
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 a
ConcurrentMap as a key or value
happen-before
actions subsequent to the access or removal of that object from
the ConcurrentMap in another thread.
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If the specified key is not already associated
with a value, associate it with the given value.
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Removes the entry for a key only if currently mapped to a given value.
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Replaces the entry for a key only if currently mapped to a given value.
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Replaces the entry for a key only if currently mapped to some value.
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Inherited Methods | |||||||||||
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From interface
java.util.Map
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If the specified key is not already associated with a value, associate it with the given value. This is equivalent to
Developers
if (!map.containsKey(key))
return map.put(key, value);
else
return map.get(key);
except that the action is performed atomically.| key | key with which the specified value is to be associated |
|---|---|
| value | value to be associated with the specified key |
null 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.)| UnsupportedOperationException | if the put operation
is not supported by this map |
|---|---|
| ClassCastException | if the class of the specified key or value prevents it from being stored in this map |
| NullPointerException | if the specified key or value is null, and this map does not permit null keys or values |
| IllegalArgumentException | if some property of the specified key or value prevents it from being stored in this map |
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.| key | key with which the specified value is associated |
|---|---|
| value | value expected to be associated with the specified key |
true if the value was removed| UnsupportedOperationException | if the remove operation
is not supported by this map |
|---|---|
| ClassCastException | if the key or value is of an inappropriate type for this map (optional) |
| NullPointerException | if the specified key or value is null, and this map does not permit null keys or values (optional) |
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.| 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 |
true if the value was replaced| UnsupportedOperationException | if the put operation
is not supported by this map |
|---|---|
| ClassCastException | if the class of a specified key or value prevents it from being stored in this map |
| NullPointerException | if a specified key or value is null, and this map does not permit null keys or values |
| IllegalArgumentException | if some property of a specified key or value prevents it from being stored in this map |
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.| key | key with which the specified value is associated |
|---|---|
| value | value to be associated with the specified key |
null 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.)| UnsupportedOperationException | if the put operation
is not supported by this map |
|---|---|
| ClassCastException | if the class of the specified key or value prevents it from being stored in this map |
| NullPointerException | if the specified key or value is null, and this map does not permit null keys or values |
| IllegalArgumentException | if some property of the specified key or value prevents it from being stored in this map |