java.util.concurrent.atomic · java.base · since Java 1.5

AtomicReference

declaration

public class AtomicReference<V> implements Serializable

Atomic object reference: CAS-swap immutable snapshots to update multi-field state without locks — the heart of nonblocking data structures.

Key methods

`boolean compareAndSet(V expect, V update)`	CAS on the reference.
`V updateAndGet(UnaryOperator<V>)`	Atomic functional swap.
`V getAndSet(V newValue)`	Swap and return old.

Example

Java

AtomicReference<Range> range = new AtomicReference<>(new Range(0, 10));
range.updateAndGet(r -> r.withUpper(20));   // multi-field invariant in ONE CAS