Atomic Operations in Java

Variables' values can become inconsistent during multithreading when multiple threads access and write to the same variable concurrently. To maintain data integrity, Java provides atomic operations that guarantee the indivisibility of certain operations. An operation is atomic if it appears to complete without being interrupted.

Atomic Operations in Java

The following operations in Java are considered atomic:

• Assignments of primitive types except for long and double
• Assignments of references
• Assignments of volatile variables
• Operations using java.concurrent.Atomic* classes, including AtomicInteger, AtomicBoolean, and AtomicReference

Limitations

It's important to note that atomicity does not imply visibility. While a partially written int variable is guaranteed not to be visible to another thread, the new value may not be visible immediately.

64-bit Values on Common CPUs

On CPUs with 64-bit architectures, operations on long and double variables are typically atomic as well. However, this is not guaranteed by the JVM specification. For more precise atomicity control, consider using AtomicLong or AtomicDouble classes from the java.concurrent.atomic package.