public abstract class

AtomicIntegerFieldUpdater

extends Object
java.lang.Object
   ↳ java.util.concurrent.atomic.AtomicIntegerFieldUpdater<T>

Class Overview

A reflection-based utility that enables atomic updates to designated 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 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.

Summary

Protected Constructors
AtomicIntegerFieldUpdater()
Protected do-nothing constructor for use by subclasses.
Public Methods
int addAndGet(T 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(T 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(T obj)
Atomically decrements by one the current value of the field of the given object managed by this updater.
abstract int get(T obj)
Gets the current value held in the field of the given object managed by this updater.
int getAndAdd(T 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(T obj)
Atomically decrements by one the current value of the field of the given object managed by this updater.
int getAndIncrement(T obj)
Atomically increments by one the current value of the field of the given object managed by this updater.
int getAndSet(T 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(T obj)
Atomically increments by one the current value of the field of the given object managed by this updater.
static <U> AtomicIntegerFieldUpdater<U> newUpdater(Class<U> tclass, String fieldName)
Creates and returns an updater for objects with the given field.
abstract void set(T obj, int newValue)
Sets the field of the given object managed by this updater to the given updated value.
abstract boolean weakCompareAndSet(T 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.
[Expand]
Inherited Methods
From class java.lang.Object

Protected Constructors

protected AtomicIntegerFieldUpdater ()

Since: API Level 1

Protected do-nothing constructor for use by subclasses.

Public Methods

public int addAndGet (T obj, int delta)

Since: API Level 1

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

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

Since: API Level 1

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
obj An object whose field to conditionally set
expect the expected value
update the new value
Returns
  • true if successful
Throws
ClassCastException if obj is not an instance of the class possessing the field established in the constructor

public int decrementAndGet (T obj)

Since: API Level 1

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

public abstract int get (T obj)

Since: API Level 1

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

public int getAndAdd (T obj, int delta)

Since: API Level 1

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

public int getAndDecrement (T obj)

Since: API Level 1

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

public int getAndIncrement (T obj)

Since: API Level 1

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

public int getAndSet (T obj, int newValue)

Since: API Level 1

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

public int incrementAndGet (T obj)

Since: API Level 1

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

public static AtomicIntegerFieldUpdater<U> newUpdater (Class<U> tclass, String fieldName)

Since: API Level 1

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
Throws
IllegalArgumentException if the field is not a volatile integer type
RuntimeException with a nested reflection-based exception if the class does not hold field or is the wrong type

public abstract void set (T obj, int newValue)

Since: API Level 1

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
obj An object whose field to set
newValue the new value

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

Since: API Level 1

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
obj An object whose field to conditionally set
expect the expected value
update the new value
Returns
  • true if successful
Throws
ClassCastException if obj is not an instance of the class possessing the field established in the constructor