Module java.base
Package java.util.concurrent.atomic

# Class AtomicIntegerFieldUpdater<T>

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 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.

Object arguments for parameters of type `T` that are not instances of the class passed to `newUpdater(java.lang.Class<U>, java.lang.String)` will result in a `ClassCastException` being thrown.

Since:
  1.5

## Constructor Summary

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

## Method Summary

Modifier and Type
Method
Description
`final int`
`accumulateAndGet(T obj, int x, IntBinaryOperator accumulatorFunction)`
Atomically updates (with memory effects as specified by `VarHandle.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.
`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)`
Returns the current value held in the field of the given object managed by this updater.
`final int`
`getAndAccumulate(T obj, int x, IntBinaryOperator accumulatorFunction)`
Atomically updates (with memory effects as specified by `VarHandle.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.
`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.
`final int`
`getAndUpdate(T obj, IntUnaryOperator updateFunction)`
Atomically updates (with memory effects as specified by `VarHandle.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.
`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.
`final int`
`updateAndGet(T obj, IntUnaryOperator updateFunction)`
Atomically updates (with memory effects as specified by `VarHandle.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 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.

### Methods declared in class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

## Constructor Details

### AtomicIntegerFieldUpdater

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

## Method Details

### 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.

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 integer 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

### 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 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

### 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 to `compareAndSet` and `set`, but not necessarily with respect to other changes in the field.

This operation 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

### 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 of `compareAndSet`.

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

### 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 set
  `newValue` - the new value
Since:
  1.6

### get

public abstract int 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

### 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 set
  `newValue` - 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

### 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 set
  `delta` - 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

### 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 set
  `delta` - the value to add
Returns:
  the updated value

### getAndUpdate

public final int getAndUpdate(T obj, IntUnaryOperator updateFunction)
Atomically updates (with memory effects as specified by `VarHandle.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

### updateAndGet

public final int updateAndGet(T obj, IntUnaryOperator updateFunction)
Atomically updates (with memory effects as specified by `VarHandle.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

### getAndAccumulate

public final int getAndAccumulate(T obj, int x, IntBinaryOperator accumulatorFunction)
Atomically updates (with memory effects as specified by `VarHandle.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

### accumulateAndGet

public final int accumulateAndGet(T obj, int x, IntBinaryOperator accumulatorFunction)
Atomically updates (with memory effects as specified by `VarHandle.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