JBang script showcasing functionality implemented in https://github.com/fabric8io/kubernetes-client/pull/2616

TestWatcher.java

///usr/bin/env jbang "$0" "$@" ; exit $?
//DEPS io.fabric8:kubernetes-client:5.0-SNAPSHOT

import static java.lang.System.*;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

import io.fabric8.kubernetes.client.KubernetesClient;
import io.fabric8.kubernetes.client.Watch;
import io.fabric8.kubernetes.client.Watcher;
import io.fabric8.kubernetes.client.WatcherException;
import io.fabric8.kubernetes.api.model.Pod;
import io.fabric8.kubernetes.client.DefaultKubernetesClient;

public class TestWatcher {

    public static void main(String... args) throws Exception {
        try (KubernetesClient kc = new DefaultKubernetesClient()) {
            final CountDownLatch cdl = new CountDownLatch(1);
            try (Watch w = kc.pods().watch(new Watcher<Pod>() {

                @Override
                public void eventReceived(Action arg0, Pod pod) {
                    out.printf("%s: %s - %s%n", Thread.currentThread().getName(), arg0, pod.getMetadata().getName());
                }

                @Override
                public void onClose(WatcherException arg0) {
                    arg0.printStackTrace();
                }
                @Override
                public void onClose() {
                    out.printf("%s: Watcher finished%n", Thread.currentThread().getName());
                    cdl.countDown();
                }
                
            })) {
                // Watcher thread should print events (if any)
                TimeUnit.SECONDS.sleep(2);
            } catch(Exception ex) {
                ex.printStackTrace();
            }
            // Watcher is being shutdown by try-with-resources close(), should eventually call the onClose method and print "Watcher finished"
            cdl.await(5, TimeUnit.SECONDS);
        }
    }
}