Java reference

ConcurrentLinkedQueue

A thread-safe, non-blocking queue.

Available since: Java 1.5

Syntax

public class ConcurrentLinkedQueue<E> implements Queue<E>

Examples

A queue filled by several threads:

void main() {
    var queue = new ConcurrentLinkedQueue<String>();
    try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
        for (int i = 0; i < 50; i++) {
            int n = i;
            executor.submit(() -> queue.offer("event-" + n));
        }
    }
    IO.println(queue.size());
    IO.println(queue.contains("event-49"));
}

Output:

50
true

Notes

poll() on an empty queue returns null without waiting for elements. If a consumer must wait for new elements, use a BlockingQueue (LinkedBlockingQueue, ArrayBlockingQueue) with put() and take(). For lists that are read often and changed rarely there is CopyOnWriteArrayList.

In the tutorial

Concurrent collections — Collections for multithreaded code in Java — ConcurrentHashMap and merge, CopyOnWriteArrayList, BlockingQueue and the producer-consumer pattern.

Thanks for reading!