Java Volatile Keyword Usage Guide

In Java, the volatile keyword is used to modify variables and ensure that multiple threads can handle the variable correctly. When a variable is marked as volatile, each access to this variable will retrieve the latest value from the main memory, instead of the thread’s working memory.

The main purpose of the ‘volatile’ keyword is to ensure the visibility of variables and prevent instruction reordering. Visibility means that when a thread modifies the value of a shared variable, other threads can immediately see this modification. Instruction reordering refers to the compiler or processor rearranging the order of instruction execution without changing the program’s outcome.

It is important to note that the volatile keyword can only ensure the visibility of variables and prevent instruction reordering, but it does not guarantee atomicity. If atomicity is needed, the synchronized keyword or the atomic classes in the Atomic package can be used.