Does the volatile modifier affect the atomicity of primitive type variables in Java?

The volatile modifier in Java guarantees that reading and writing a variable will happen directly from main memory, ensuring visibility of changes between threads. However, it does not guarantee atomicity of operations on variables, except for reading and writing primitive types of 32 bits or less (e.g., int, boolean).

For primitive types like long and double, which occupy 64 bits, read and write operations without volatile may not be atomic, but with volatile they become atomic.

Important:

• volatile guarantees atomicity only for read and write operations, not for compound operations (e.g., increment x++).
• For atomic compound operations, synchronization or classes from java.util.concurrent.atomic should be used.

Example:

volatile int counter;

// counter++ is not an atomic operation, even if counter is declared volatile