Atomic Access Java Tutorial states “In programming, an atomic action is one that effectively happens all at once. An atomic action cannot stop in the middle: it either happens completely, or it doesn't happen at all. No side effects of an atomic action are visible until the action is complete”.
Let’s assume we are writing a multi threaded program. Let’s create an int variable i. Even a small operation, like i++ (increment), is not thread safe. i++ operation involves three steps.
* Read the value which is currently stored in i
* Add one to it (atomic operation).
* Store it in i
In a multi-threaded environment, there can be unexpected results. For example, if thread1 is reading the value (step 1) and immediately after thread2 stores the value (step 3).
To prevent these, Java provides atomic operations. Atomic operations are performed as a single unit without interference from other threads ensuring data consistency.
A good example is AtomicInteger. To increment a value of AtomicInteger, we use the incrementAndGet() method. Java ensures this operation is Atomic.
