- java.lang.Object
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- java.util.concurrent.atomic.AtomicLongFieldUpdater<T>
 
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- Type Parameters:
- T- The type of the object holding the updatable field
 
 public abstract class AtomicLongFieldUpdater<T> extends Object A reflection-based utility that enables atomic updates to designatedvolatile longfields 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 compareAndSetmethod 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 ofcompareAndSetandseton the same updater.Object arguments for parameters of type Tthat are not instances of the class passed tonewUpdater(java.lang.Class<U>, java.lang.String)will result in aClassCastExceptionbeing thrown.- Since:
- 1.5
 
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Constructor SummaryConstructors Modifier Constructor Description protectedAtomicLongFieldUpdater()Protected do-nothing constructor for use by subclasses.
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Method SummaryAll Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description longaccumulateAndGet(T obj, long x, LongBinaryOperator accumulatorFunction)Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the updated value.longaddAndGet(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 booleancompareAndSet(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.longdecrementAndGet(T obj)Atomically decrements by one the current value of the field of the given object managed by this updater.abstract longget(T obj)Returns the current value held in the field of the given object managed by this updater.longgetAndAccumulate(T obj, long x, LongBinaryOperator accumulatorFunction)Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the previous value.longgetAndAdd(T obj, long delta)Atomically adds the given value to the current value of the field of the given object managed by this updater.longgetAndDecrement(T obj)Atomically decrements by one the current value of the field of the given object managed by this updater.longgetAndIncrement(T obj)Atomically increments by one the current value of the field of the given object managed by this updater.longgetAndSet(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.longgetAndUpdate(T obj, LongUnaryOperator updateFunction)Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function, returning the previous value.longincrementAndGet(T obj)Atomically increments by one the current value of the field of the given object managed by this updater.abstract voidlazySet(T obj, long newValue)Eventually sets the field of the given object managed by this updater to the given updated value.static <U> AtomicLongFieldUpdater<U>newUpdater(Class<U> tclass, String fieldName)Creates and returns an updater for objects with the given field.abstract voidset(T obj, long newValue)Sets the field of the given object managed by this updater to the given updated value.longupdateAndGet(T obj, LongUnaryOperator updateFunction)Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function, returning the updated value.abstract booleanweakCompareAndSet(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.
 
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Method Detail- 
newUpdaterpublic 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.- Type Parameters:
- U- the type of instances of tclass
- 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 long type
- RuntimeException- with a nested reflection-based exception if the class does not hold field or is the wrong type, or the field is inaccessible to the caller according to Java language access control
 
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compareAndSetpublic 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 tocompareAndSetandset, 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:
- trueif successful
 
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weakCompareAndSetpublic 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 tocompareAndSetandset, 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:
- trueif successful
 
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setpublic 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 ofcompareAndSet.- Parameters:
- obj- An object whose field to set
- newValue- the new value
 
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lazySetpublic abstract void lazySet(T obj, long 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
- Since:
- 1.6
 
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getpublic abstract long get(T obj) Returns 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
 
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getAndSetpublic 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:
- obj- An object whose field to get and set
- newValue- the new value
- Returns:
- the previous value
 
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getAndIncrementpublic long 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
 
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getAndDecrementpublic long 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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getAndAddpublic 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:
- obj- An object whose field to get and set
- delta- the value to add
- Returns:
- the previous value
 
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incrementAndGetpublic long 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
 
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decrementAndGetpublic long 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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addAndGetpublic 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:
- obj- An object whose field to get and set
- delta- the value to add
- Returns:
- the updated value
 
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getAndUpdatepublic final long getAndUpdate(T obj, LongUnaryOperator updateFunction) Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function, returning the previous value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads.- Parameters:
- obj- An object whose field to get and set
- updateFunction- a side-effect-free function
- Returns:
- the previous value
- Since:
- 1.8
 
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updateAndGetpublic final long updateAndGet(T obj, LongUnaryOperator updateFunction) Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function, returning the updated value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads.- Parameters:
- obj- An object whose field to get and set
- updateFunction- a side-effect-free function
- Returns:
- the updated value
- Since:
- 1.8
 
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getAndAccumulatepublic final long getAndAccumulate(T obj, long x, LongBinaryOperator accumulatorFunction) Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the previous value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads. The function is applied with the current value as its first argument, and the given update as the second argument.- Parameters:
- obj- An object whose field to get and set
- x- the update value
- accumulatorFunction- a side-effect-free function of two arguments
- Returns:
- the previous value
- Since:
- 1.8
 
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accumulateAndGetpublic final long accumulateAndGet(T obj, long x, LongBinaryOperator accumulatorFunction) Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the updated value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads. The function is applied with the current value as its first argument, and the given update as the second argument.- Parameters:
- obj- An object whose field to get and set
- x- the update value
- accumulatorFunction- a side-effect-free function of two arguments
- Returns:
- the updated value
- Since:
- 1.8
 
 
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