BAEL-679. Java 9 Reactive Streams. Second draft.

core-java-9/src/main/java/com/baeldung/java9/reactive/BaeldungBatchSubscriberImpl.java

@@ -0,0 +1,84 @@
+package com.baeldung.java9.reactive;
+
+import java.util.ArrayList;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+
+public class BaeldungBatchSubscriberImpl<T> implements Subscriber<String> {
+    private Subscription subscription;
+    private boolean completed = false;
+    private int counter;
+    private ArrayList<String> buffer;
+    public static final int BUFFER_SIZE = 5;
+
+    public BaeldungBatchSubscriberImpl() {
+        buffer = new ArrayList<String>();
+    }
+
+    public boolean isCompleted() {
+        return completed;
+    }
+
+    public void setCompleted(boolean completed) {
+        this.completed = completed;
+    }
+
+    public int getCounter() {
+        return counter;
+    }
+
+    public void setCounter(int counter) {
+        this.counter = counter;
+    }
+
+    @Override
+    public void onSubscribe(Subscription subscription) {
+        this.subscription = subscription;
+        subscription.request(BUFFER_SIZE);
+    }
+
+    @Override
+    public void onNext(String item) {
+        buffer.add(item);
+        // if buffer is full, process the items.
+        if (buffer.size() >= BUFFER_SIZE) {
+            processBuffer();
+            subscription.request(BUFFER_SIZE);
+        } else if(buffer.size() == 0) {
+            // If buffer empty, request more items.
+            subscription.request(BUFFER_SIZE);
+        }
+    }
+
+    private void processBuffer() {
+        if (buffer.isEmpty())
+            return;
+        // Process all items in the buffer. Here, we just print it and sleep for 1 second.
+        System.out.print("Processed items: ");
+        buffer.stream()
+            .forEach(item -> {
+                System.out.print(" " + item);
+            });
+        System.out.println();
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        counter = counter + buffer.size();
+        buffer.clear();
+    }
+
+    @Override
+    public void onError(Throwable t) {
+        t.printStackTrace();
+    }
+
+    @Override
+    public void onComplete() {
+        completed = true;
+        // process any remaining items in buffer before
+        processBuffer();
+        subscription.cancel();
+    }
+}

core-java-9/src/main/java/com/baeldung/java9/reactive/BaeldungSubscriberImpl.java

@@ -0,0 +1,55 @@
+package com.baeldung.java9.reactive;
+
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+
+public class BaeldungSubscriberImpl<T> implements Subscriber<String> {
+    private Subscription subscription;
+    private boolean completed = false;
+    private int counter;
+
+    public boolean isCompleted() {
+        return completed;
+    }
+
+    public void setCompleted(boolean completed) {
+        this.completed = completed;
+    }
+
+    public int getCounter() {
+        return counter;
+    }
+
+    public void setCounter(int counter) {
+        this.counter = counter;
+    }
+
+    @Override
+    public void onSubscribe(Subscription subscription) {
+        this.subscription = subscription;
+        subscription.request(1);
+    }
+
+    @Override
+    public void onNext(String item) {
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        counter++;
+        System.out.println("Processed item : " + item);
+        subscription.request(1);
+    }
+
+    @Override
+    public void onError(Throwable t) {
+        t.printStackTrace();
+    }
+
+    @Override
+    public void onComplete() {
+        completed = true;
+        subscription.cancel();
+    }
+}