AtomicIntegerFieldUpdater (Java Platform SE 6)

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java.util.concurrent.atomic
class AtomicIntegerFieldUpdater

java.lang.Object
  java.util.concurrent.atomic.AtomicIntegerFieldUpdater

public abstract class AtomicIntegerFieldUpdater
extends Object

A reflection-based utility that enables atomic updates to designated {@code volatile int} 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 {@code 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 {@code compareAndSet} and {@code set} on the same updater.

Constructor Summary
`protected`	`AtomicIntegerFieldUpdater()` Protected do-nothing constructor for use by subclasses.

Method Summary
`int`	`addAndGet(Object obj, int delta)` Atomically adds the given value to the current value of the field of the given object managed by this updater.
`abstract boolean`	`compareAndSet(Object obj, int expect, int 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.
`int`	`decrementAndGet(Object obj)` Atomically decrements by one the current value of the field of the given object managed by this updater.
`abstract int`	`get(Object obj)` Gets the current value held in the field of the given object managed by this updater.
`int`	`getAndAdd(Object obj, int delta)` Atomically adds the given value to the current value of the field of the given object managed by this updater.
`int`	`getAndDecrement(Object obj)` Atomically decrements by one the current value of the field of the given object managed by this updater.
`int`	`getAndIncrement(Object obj)` Atomically increments by one the current value of the field of the given object managed by this updater.
`int`	`getAndSet(Object obj, int newValue)` Atomically sets the field of the given object managed by this updater to the given value and returns the old value.
`int`	`incrementAndGet(Object obj)` Atomically increments by one the current value of the field of the given object managed by this updater.
`abstract void`	`lazySet(Object obj, int newValue)` Eventually sets the field of the given object managed by this updater to the given updated value.
`static AtomicIntegerFieldUpdater`	`newUpdater(Class tclass, String fieldName)` Creates and returns an updater for objects with the given field.
`abstract void`	`set(Object obj, int newValue)` Sets the field of the given object managed by this updater to the given updated value.
`abstract boolean`	`weakCompareAndSet(Object obj, int expect, int 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 class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

AtomicIntegerFieldUpdater

protected AtomicIntegerFieldUpdater()

Protected do-nothing constructor for use by subclasses.

Method Detail

addAndGet

public int addAndGet(Object obj,
                     int delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater.

Parameters:: obj - An object whose field to get and set; delta - the value to add
Returns:: the updated value

compareAndSet

public abstract boolean compareAndSet(Object obj,
                                      int expect,
                                      int update)

Atomically sets the field of the given object managed by this updater to the given updated value if the current value {@code ==} the expected value. This method is guaranteed to be atomic with respect to other calls to {@code compareAndSet} and {@code set}, but not necessarily with respect to other changes in the field.

Parameters:: obj - An object whose field to conditionally set; expect - the expected value; update - the new value
Returns:: true if successful

decrementAndGet

public int decrementAndGet(Object obj)

Atomically decrements by one the current value of the field of the given object managed by this updater.

Parameters:: obj - An object whose field to get and set
Returns:: the updated value

get

public abstract int get(Object obj)

Gets the current value held in the field of the given object managed by this updater.

Parameters:: obj - An object whose field to get
Returns:: the current value

getAndAdd

public int getAndAdd(Object obj,
                     int delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater.

Parameters:: obj - An object whose field to get and set; delta - the value to add
Returns:: the previous value

getAndDecrement

public int getAndDecrement(Object obj)

Atomically decrements by one the current value of the field of the given object managed by this updater.

Parameters:: obj - An object whose field to get and set
Returns:: the previous value

getAndIncrement

public int getAndIncrement(Object obj)

Atomically increments by one the current value of the field of the given object managed by this updater.

Parameters:: obj - An object whose field to get and set
Returns:: the previous value

getAndSet

public int getAndSet(Object obj,
                     int newValue)

Atomically sets the field of the given object managed by this updater to the given value and returns the old value.

Parameters:: obj - An object whose field to get and set; newValue - the new value
Returns:: the previous value

incrementAndGet

public int incrementAndGet(Object obj)

Atomically increments by one the current value of the field of the given object managed by this updater.

Parameters:: obj - An object whose field to get and set
Returns:: the updated value

lazySet

public abstract void lazySet(Object obj,
                             int newValue)

Eventually sets the field of the given object managed by this updater to the given updated value.

Parameters:: obj - An object whose field to set; newValue - the new value

newUpdater

public static AtomicIntegerFieldUpdater newUpdater(Class 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:: tclass - the class of the objects holding the field; fieldName - the name of the field to be updated
Returns:: the updater

set

public abstract void set(Object obj,
                         int 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 {@code compareAndSet}.

Parameters:: obj - An object whose field to set; newValue - the new value

weakCompareAndSet

public abstract boolean weakCompareAndSet(Object obj,
                                          int expect,
                                          int update)

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

Parameters:: obj - An object whose field to conditionally set; expect - the expected value; update - the new value
Returns:: true if successful