Collections.Map.Concurrent.putIfAbsent()
Signature
Object putIfAbsent ( Object map ,Object key ,Object value )
Description
If the specified key is not already associated with a value, associate it with the given value. The action is performed atomically.
Parameters
| Name | Type | Description |
|---|
map | Object | The concurrent map object |
key | Object | key with which the specified value is to be associated. |
value | Object | value to be associated with the specified key. |
Returns
| Type | Description |
|---|
Object | previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values. |