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java.util.concurrent.atomic
Class AtomicLongFieldUpdater
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public abstract class AtomicLongFieldUpdater<T>
Type Parameters:
  • T - The type of the object holding the updatable field
A reflection-based utility that enables atomic updates to designated volatile long fields of designated classes. This class is designed for use in atomic data structures in which several fields of the same node are independently subject to atomic updates.

Note that the guarantees of the compareAndSet method in this class are weaker than in other atomic classes. Because this class cannot ensure that all uses of the field are appropriate for purposes of atomic access, it can guarantee atomicity only with respect to other invocations of compareAndSet and set on the same updater.

Since1.5
VersionNot specified.
AuthorDoug Lea
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Constructor Summary
AtomicLongFieldUpdater()
Protected do-nothing constructor for use by subclasses.
Method Summary
long addAndGet( T obj, long delta )
Atomically adds the given value to the current value of the field of the given object managed by this updater.
abstract boolean compareAndSet( T obj, long expect, long update )
Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value.
long decrementAndGet( T obj )
Atomically decrements by one the current value of the field of the given object managed by this updater.
abstract long get( T obj )
Gets the current value held in the field of the given object managed by this updater.
long getAndAdd( T obj, long delta )
Atomically adds the given value to the current value of the field of the given object managed by this updater.
long getAndDecrement( T obj )
Atomically decrements by one the current value of the field of the given object managed by this updater.
long getAndIncrement( T obj )
Atomically increments by one the current value of the field of the given object managed by this updater.
long getAndSet( T obj, long newValue )
Atomically sets the field of the given object managed by this updater to the given value and returns the old value.
long incrementAndGet( T obj )
Atomically increments by one the current value of the field of the given object managed by this updater.
abstract void lazySet( T obj, long newValue )
Eventually sets the field of the given object managed by this updater to the given updated value.
static AtomicLongFieldUpdater<U> newUpdater( Class<U> tclass, String fieldName )
Creates and returns an updater for objects with the given field.
abstract void set( T obj, long newValue )
Sets the field of the given object managed by this updater to the given updated value.
abstract boolean weakCompareAndSet( T obj, long expect, long update )
Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value.
Methods inherited from java.langObject
Constructor Detail
AtomicLongFieldUpdater
protected AtomicLongFieldUpdater ( )
Protected do-nothing constructor for use by subclasses.
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Method Detail
addAndGet
public long addAndGet ( T obj, long delta )
Atomically adds the given value to the current value of the field of the given object managed by this updater.
Parameters
TypeNameDescription
T obj An object whose field to get and set
long delta the value to add
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compareAndSet
public abstract boolean compareAndSet ( T obj, long expect, long update )
Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value. This method is guaranteed to be atomic with respect to other calls to compareAndSet and set , but not necessarily with respect to other changes in the field.
Parameters
TypeNameDescription
T obj An object whose field to conditionally set
long expect the expected value
long update the new value
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decrementAndGet
public long decrementAndGet ( T obj )
Atomically decrements by one the current value of the field of the given object managed by this updater.
Parameters
TypeNameDescription
T obj An object whose field to get and set
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get
public abstract long get ( T obj )
Gets the current value held in the field of the given object managed by this updater.
Parameters
TypeNameDescription
T obj An object whose field to get
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getAndAdd
public long getAndAdd ( T obj, long delta )
Atomically adds the given value to the current value of the field of the given object managed by this updater.
Parameters
TypeNameDescription
T obj An object whose field to get and set
long delta the value to add
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getAndDecrement
public long getAndDecrement ( T obj )
Atomically decrements by one the current value of the field of the given object managed by this updater.
Parameters
TypeNameDescription
T obj An object whose field to get and set
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getAndIncrement
public long getAndIncrement ( T obj )
Atomically increments by one the current value of the field of the given object managed by this updater.
Parameters
TypeNameDescription
T obj An object whose field to get and set
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getAndSet
public long getAndSet ( T obj, long newValue )
Atomically sets the field of the given object managed by this updater to the given value and returns the old value.
Parameters
TypeNameDescription
T obj An object whose field to get and set
long newValue the new value
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incrementAndGet
public long incrementAndGet ( T obj )
Atomically increments by one the current value of the field of the given object managed by this updater.
Parameters
TypeNameDescription
T obj An object whose field to get and set
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lazySet
public abstract void lazySet ( T obj, long newValue )
Eventually sets the field of the given object managed by this updater to the given updated value.
Since: 1.6
Parameters
TypeNameDescription
T obj An object whose field to set
long newValue the new value
Returns void No description provided.
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newUpdater
public static <U> AtomicLongFieldUpdater<U> newUpdater ( Class<U> tclass, String fieldName )
Creates and returns an updater for objects with the given field. The Class argument is needed to check that reflective types and generic types match.
Parameters
TypeNameDescription
Class<U> tclass the class of the objects holding the field
String fieldName the name of the field to be updated.
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set
public abstract void set ( T obj, long newValue )
Sets the field of the given object managed by this updater to the given updated value. This operation is guaranteed to act as a volatile store with respect to subsequent invocations of compareAndSet .
Parameters
TypeNameDescription
T obj An object whose field to set
long newValue the new value
Returns void No description provided.
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weakCompareAndSet
public abstract boolean weakCompareAndSet ( T obj, long expect, long update )
Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value. This method is guaranteed to be atomic with respect to other calls to compareAndSet and set , but not necessarily with respect to other changes in the field.

May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to compareAndSet .

Parameters
TypeNameDescription
T obj An object whose field to conditionally set
long expect the expected value
long update the new value
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