What methods of thread synchronization do you know in Java?

In Java, there are several ways to synchronize threads:

• The synchronized keyword — locks methods or blocks of code to ensure mutual exclusion.

• Lock objects from java.util.concurrent.locks — a more flexible locking mechanism, such as ReentrantLock, allowing attempts to acquire the lock with a timeout, checking the lock state, etc.

• Volatile — guarantees visibility of variable changes between threads but does not ensure atomicity.

• Atomic classes (AtomicInteger, AtomicReference, etc.) — provide atomic operations without locks.

• Semaphores — limit the number of threads executing a certain section of code simultaneously.

• CountDownLatch, CyclicBarrier — for thread coordination, waiting for events.

• Concurrent collections (ConcurrentHashMap, ConcurrentLinkedQueue, etc.) — provide thread-safe access without external synchronization.

Example of using synchronized:

public class Counter {
    private int count = 0;

    public synchronized void increment() {
        count++;
    }

    public synchronized int getCount() {
        return count;
    }
}

The choice of method depends on the task: for simple mutual exclusion, synchronized is suitable; for more complex scenarios, Lock or atomic classes are preferable.