What is the volatile keyword in Java?

What is the volatile keyword in Java?

The volatile keyword in Java is used to indicate that a variable's value will be modified by different threads. It ensures that the most recent value is always read from the main memory, rather than from a thread's local cache.

Why should I use volatile instead of synchronized?

Using volatile is generally more lightweight than synchronized. It provides a simpler way to ensure visibility of changes to variables across threads without the overhead of acquiring locks.

Can you give me an example of using volatile?

Sure! Here's a simple example:

public class Example {
    private volatile boolean running = true;

    public void run() {
        while (running) {
            // do something
        }
    }

    public void stop() {
        running = false;
    }
}

In this example, the running variable is marked as volatile to ensure that changes made in one thread are visible to others.

Are there any downsides to using volatile?

Yes, while volatile ensures visibility, it does not guarantee atomicity. If you need to perform compound actions (like incrementing a variable), you should use synchronized blocks or other concurrency mechanisms.