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

AtomicInteger

declaration

public class AtomicInteger extends Number implements Serializable

Lock-free int with atomic read-modify-write (CAS): counters, sequence numbers, state flags — volatile semantics plus atomicity.

Key methods

`int incrementAndGet() / getAndIncrement()`	Atomic ++ (pre/post).
`boolean compareAndSet(int expect, int update)`	The CAS primitive.
`int updateAndGet(IntUnaryOperator)`	Atomic functional update (pure function — may retry).
`int addAndGet(int delta)`	Atomic +=.