⚡ volatile Keyword in Java

? Quick Overview

The volatile keyword in Java is used in multithreading to ensure that changes made to a variable by one thread are immediately visible to other threads.

? Key Concepts

• Ensures visibility of shared variables across threads
• Prevents thread-local caching of variables
• Does not provide atomicity
• Mainly used in low-level concurrency control

? Syntax / Theory

When a variable is declared as volatile, the JVM reads it directly from main memory instead of thread cache.

// Declaring a volatile variable for thread visibility
public class SharedData {
volatile boolean running = true;
}

? Code Example(s)

// Demonstrates how volatile ensures visibility between threads
class Worker extends Thread {
volatile boolean active = true;

public void run() {
while (active) {
}
System.out.println("Thread stopped");
}

public void stopWorker() {
active = false;
}
}

? Live Output / Explanation