advconcurrency5Exchanger

1package pkg16advconcurrency;2 3import java.util.concurrent.Exchanger;4import java.util.concurrent.ExecutorService;5import java.util.concurrent.Executors;6import java.util.concurrent.TimeUnit;7 8/*9 * advconcurrency5Exchanger.java10 * -----------------------------11 * Exchanger: two threads swap objects at a synchronization point.12 *13 * DEFINITION:14 *   exchange(V) blocks until another thread also calls exchange, then both receive15 *   the other's value. Only two parties per exchanger instance.16 *17 * KEY POINTS:18 *   - Classic use: producer fills buffer, consumer takes buffer, swap empty/full.19 *   - exchange(timeout) avoids indefinite wait.20 *   - For N-way exchange use other structures (queues).21 */22public class advconcurrency5Exchanger {23 24    public static void main(String[] args) throws InterruptedException {25        Exchanger<String> exchanger = new Exchanger<>();26 27        try (ExecutorService pool = Executors.newFixedThreadPool(2)) {28            pool.submit(() -> {29                try {30                    String received = exchanger.exchange("from-A");31                    System.out.println("Thread A received: " + received);32                } catch (InterruptedException e) {33                    Thread.currentThread().interrupt();34                }35            });36            pool.submit(() -> {37                try {38                    Thread.sleep(100);39                    String received = exchanger.exchange("from-B");40                    System.out.println("Thread B received: " + received);41                } catch (InterruptedException e) {42                    Thread.currentThread().interrupt();43                }44            });45            pool.shutdown();46            pool.awaitTermination(3, TimeUnit.SECONDS);47        }48    }49}