- java.lang.Object
-
- java.util.concurrent.atomic.AtomicIntegerFieldUpdater<T>
-
- Type Parameters:
T
- The type of the object holding the updatable field
public abstract class AtomicIntegerFieldUpdater<T> extends Object
A reflection-based utility that enables atomic updates to designatedvolatile 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 ofcompareAndSet
andset
on the same updater.- Since:
- 1.5
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-
Constructor Summary
Constructors Modifier Constructor and Description protected
AtomicIntegerFieldUpdater()
Protected do-nothing constructor for use by subclasses.
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Method Summary
Methods Modifier and Type Method and Description 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.abstract void
lazySet(T obj, int newValue)
Eventually sets the field of the given object managed by this updater to the given updated value.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.
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Constructor Detail
-
AtomicIntegerFieldUpdater
protected AtomicIntegerFieldUpdater()
Protected do-nothing constructor for use by subclasses.
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Method Detail
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newUpdater
public static <U> AtomicIntegerFieldUpdater<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:
tclass
- the class of the objects holding the fieldfieldName
- the name of the field to be updated- Returns:
- the updater
- Throws:
IllegalArgumentException
- if the field is not a volatile integer typeRuntimeException
- with a nested reflection-based exception if the class does not hold field or is the wrong type
-
compareAndSet
public 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. This method is guaranteed to be atomic with respect to other calls tocompareAndSet
andset
, but not necessarily with respect to other changes in the field.- Parameters:
obj
- An object whose field to conditionally setexpect
- the expected valueupdate
- the new value- Returns:
- true if successful
- Throws:
ClassCastException
- ifobj
is not an instance of the class possessing the field established in the constructor
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weakCompareAndSet
public 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. This method is guaranteed to be atomic with respect to other calls tocompareAndSet
andset
, 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 setexpect
- the expected valueupdate
- the new value- Returns:
- true if successful
- Throws:
ClassCastException
- ifobj
is not an instance of the class possessing the field established in the constructor
-
set
public abstract void set(T 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 ofcompareAndSet
.- Parameters:
obj
- An object whose field to setnewValue
- the new value
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lazySet
public abstract void lazySet(T 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 setnewValue
- the new value- Since:
- 1.6
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get
public abstract int get(T 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
-
getAndSet
public 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.- Parameters:
obj
- An object whose field to get and setnewValue
- the new value- Returns:
- the previous value
-
getAndIncrement
public int getAndIncrement(T 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
-
getAndDecrement
public int getAndDecrement(T 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
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getAndAdd
public 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.- Parameters:
obj
- An object whose field to get and setdelta
- the value to add- Returns:
- the previous value
-
incrementAndGet
public int incrementAndGet(T 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
-
decrementAndGet
public int decrementAndGet(T 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
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addAndGet
public 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.- Parameters:
obj
- An object whose field to get and setdelta
- the value to add- Returns:
- the updated value
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Vielen Dank im Voraus.
Dokument erstellt 11/06/2005, zuletzt geändert 04/03/2020
Quelle des gedruckten Dokuments:https://www.gaudry.be/de/java-api-rf-java/util/concurrent/atomic/AtomicIntegerFieldUpdater.html
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