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🏷 Async Programming 4 patterns

Topic: Async Programming

All Java patterns related to Async Programming — java.evolved

CompletableFuture chaining

Old Future<String> future = executor.submit(this::fetchData); String data = future.get(); // blocks String result = transform(data);

Modern CompletableFuture.supplyAsync( this::fetchData ) .thenApply(this::transform) .thenAccept(IO::println);

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JDK 8+ learn more →

Unsafe thread termination to cooperative cancellation

Old Thread worker = new Thread(this::runTask); worker.start(); // May stop the thread while shared state is inconsistent. worker.stop();

Modern Future<?> worker = executor.submit(this::runTask); // Requests interruption; the task must cooperate. worker.cancel(true);

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JDK 5+ learn more →

WebSocket clients with java.net.http

Old WebSocketClient client = new WebSocketClient(serverUri) { @Override public void onMessage(String message) { handle(message); } }; client.connect();

Modern HttpClient.newHttpClient() .newWebSocketBuilder() .buildAsync(serverUri, new WebSocket.Listener() { @Override public CompletionStage<?> onText( WebSocket socket, CharSequence data, boolean last) { handle(data.toString()); return WebSocket.Listener.super .onText(socket, data, last); } });

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JDK 11+ learn more →

Message-Driven Bean vs Reactive Messaging

Old @MessageDriven(activationConfig = { @ActivationConfigProperty( propertyName = "destinationType", propertyValue = "jakarta.jms.Queue"), @ActivationConfigProperty( propertyName = "destination", propertyValue = "java:/jms/OrderQueue") }) public class OrderMDB implements MessageListener { @Override public void onMessage(Message message) { TextMessage txt = (TextMessage) message; processOrder(txt.getText()); } }

Modern @ApplicationScoped public class OrderProcessor { @Incoming("orders") public void process(Order order) { // automatically deserialized from // the "orders" channel fulfillOrder(order); } }

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JDK 11+ learn more →