Utilidades de Concurrencia

import java.util.concurrent.*;
import java.util.concurrent.atomic.*;

// ExecutorService
ExecutorService executor = Executors.newFixedThreadPool(4);
Future<Integer> future = executor.submit(() -> {
    Thread.sleep(1000);
    return 42;
});
Integer result = future.get(2, TimeUnit.SECONDS);
executor.shutdown();

// CompletableFuture
CompletableFuture.supplyAsync(() -> "Hello")
    .thenApply(s -> s + " World")
    .thenAccept(System.out::println);

// AtomicInteger
AtomicInteger counter = new AtomicInteger(0);
counter.incrementAndGet();
counter.compareAndSet(1, 10);

// CountDownLatch
CountDownLatch latch = new CountDownLatch(3);
for (int i = 0; i < 3; i++) {
    new Thread(() -> { latch.countDown(); }).start();
}
latch.await();