File	Doc	Category	Size	Date	Package
AtomicReferenceFieldUpdater.java	API Doc	Java SE 6 API	10510	Tue Jun 10 00:25:58 BST 2008	java.util.concurrent.atomic

AtomicReferenceFieldUpdater

• java.lang.Object

class Node {
private volatile Node left, right;

private static final AtomicReferenceFieldUpdater<Node, Node> leftUpdater =
AtomicReferenceFieldUpdater.newUpdater(Node.class, Node.class, "left");
private static AtomicReferenceFieldUpdater<Node, Node> rightUpdater =
AtomicReferenceFieldUpdater.newUpdater(Node.class, Node.class, "right");

Node getLeft() { return left; }
boolean compareAndSetLeft(Node expect, Node update) {
return leftUpdater.compareAndSet(this, expect, update);
}
// ... and so on
}

Fields Summary

Constructors Summary
protected AtomicReferenceFieldUpdater() Protected do-nothing constructor for use by subclasses.

Methods Summary
public abstract boolean	compareAndSet(T obj, V expect, V 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. param obj An object whose field to conditionally set param expect the expected value param update the new value return true if successful.
public abstract V	get(T obj) Gets the current value held in the field of the given object managed by this updater. param obj An object whose field to get return the current value
public V	getAndSet(T obj, V newValue) Atomically sets the field of the given object managed by this updater to the given value and returns the old value. param obj An object whose field to get and set param newValue the new value return the previous value for (;;) { V current = get(obj); if (compareAndSet(obj, current, newValue)) return current; }
public abstract void	lazySet(T obj, V newValue) Eventually sets the field of the given object managed by this updater to the given updated value. param obj An object whose field to set param newValue the new value since 1.6
public static java.util.concurrent.atomic.AtomicReferenceFieldUpdater	newUpdater(java.lang.Class tclass, java.lang.Class vclass, java.lang.String fieldName) Creates and returns an updater for objects with the given field. The Class arguments are needed to check that reflective types and generic types match. param tclass the class of the objects holding the field. param vclass the class of the field param fieldName the name of the field to be updated. return the updater throws IllegalArgumentException if the field is not a volatile reference type. throws RuntimeException with a nested reflection-based exception if the class does not hold field or is the wrong type. return new AtomicReferenceFieldUpdaterImpl<U,W>(tclass, vclass, fieldName);
public abstract void	set(T obj, V 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}. param obj An object whose field to set param newValue the new value
public abstract boolean	weakCompareAndSet(T obj, V expect, V 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. May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to {@code compareAndSet}. param obj An object whose field to conditionally set param expect the expected value param update the new value return true if successful.