Is iinc atomic in Java?

Question

I know increment operation is not atomic in C++ without locking.

Will JVM add any lock on its implementation of iinc instruction?

Answer 1

i++ is not atomic in java.
It is better to use

AtomicInteger atomic= new AtomicInteger(1);

There are methods defined like

atomic.getAndDecrement();
atomic.getAndIncrement();
atomic.decrementAndGet();
atomic.incrementAndGet();

any operation with above method would be atomic.

This class comes under java.util.concurrent.atomic package. Java 1.5 has added many features for thready safety and thread concurrency.