👀 Views: 2 💬 Answers: 1 📅 Created: 2025-06-07

java multithreading synchronization Java

I'm sure I'm missing something obvious here, but I'm facing an issue with synchronization in my multi-threaded Java application. I have a method that updates a shared resource, and I'm using synchronized blocks to ensure thread safety. However, I'm seeing inconsistent results, and sometimes my updates aren't reflected as expected. Here’s a simplified version of my code: ```java public class SharedResource { private int counter = 0; public synchronized void increment() { counter++; } public synchronized int getCounter() { return counter; } } public class Worker implements Runnable { private SharedResource resource; public Worker(SharedResource resource) { this.resource = resource; } @Override public void run() { for (int i = 0; i < 1000; i++) { resource.increment(); } } } public class Main { public static void main(String[] args) throws InterruptedException { SharedResource resource = new SharedResource(); Thread t1 = new Thread(new Worker(resource)); Thread t2 = new Thread(new Worker(resource)); t1.start(); t2.start(); t1.join(); t2.join(); System.out.println("Final counter: " + resource.getCounter()); } } ``` When I run the above code, I often see the final counter value printed as less than 2000, which is unexpected. I expected that the synchronized blocks would prevent any concurrent modifications. I've also tried using `ReentrantLock` instead of synchronized blocks, but I get similar results. Is there something I’m missing? Could it be a race condition despite using synchronized methods? Are there best practices I should follow to ensure that updates to the counter are accurately reflected in a multi-threaded environment? Any insights would be greatly appreciated! My development environment is macOS.